diff --git a/src/field_10x26_impl.h b/src/field_10x26_impl.h
index ed7e3d2c57f4d..3f942b0d47772 100644
--- a/src/field_10x26_impl.h
+++ b/src/field_10x26_impl.h
@@ -51,8 +51,8 @@ static void secp256k1_fe_normalize(secp256k1_fe_t *r) {
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
     /* Reduce t9 at the start so there will be at most a single carry from the first pass */
-    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
     uint32_t m;
+    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x3D1UL; t1 += (x << 6);
@@ -137,8 +137,8 @@ static void secp256k1_fe_normalize_var(secp256k1_fe_t *r) {
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
     /* Reduce t9 at the start so there will be at most a single carry from the first pass */
-    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
     uint32_t m;
+    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x3D1UL; t1 += (x << 6);
@@ -192,12 +192,12 @@ static int secp256k1_fe_normalizes_to_zero(secp256k1_fe_t *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
-    /* Reduce t9 at the start so there will be at most a single carry from the first pass */
-    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
-
     /* z0 tracks a possible raw value of 0, z1 tracks a possible raw value of P */
     uint32_t z0, z1;
 
+    /* Reduce t9 at the start so there will be at most a single carry from the first pass */
+    uint32_t x = t9 >> 22; t9 &= 0x03FFFFFUL;
+
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x3D1UL; t1 += (x << 6);
     t1 += (t0 >> 26); t0 &= 0x3FFFFFFUL; z0  = t0; z1  = t0 ^ 0x3D0UL;
@@ -218,23 +218,36 @@ static int secp256k1_fe_normalizes_to_zero(secp256k1_fe_t *r) {
 }
 
 static int secp256k1_fe_normalizes_to_zero_var(secp256k1_fe_t *r) {
-    uint32_t t0 = r->n[0], t9 = r->n[9];
+    uint32_t t0, t1, t2, t3, t4, t5, t6, t7, t8, t9;
+    uint32_t z0, z1;
+    uint32_t x;
+
+    t0 = r->n[0];
+    t9 = r->n[9];
 
     /* Reduce t9 at the start so there will be at most a single carry from the first pass */
-    uint32_t x = t9 >> 22;
+    x = t9 >> 22;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x3D1UL;
 
     /* z0 tracks a possible raw value of 0, z1 tracks a possible raw value of P */
-    uint32_t z0 = t0 & 0x3FFFFFFUL, z1 = z0 ^ 0x3D0UL;
+    z0 = t0 & 0x3FFFFFFUL;
+    z1 = z0 ^ 0x3D0UL;
 
     /* Fast return path should catch the majority of cases */
     if ((z0 != 0UL) & (z1 != 0x3FFFFFFUL))
         return 0;
 
-    uint32_t t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
-             t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8];
+    t1 = r->n[1];
+    t2 = r->n[2];
+    t3 = r->n[3];
+    t4 = r->n[4];
+    t5 = r->n[5];
+    t6 = r->n[6];
+    t7 = r->n[7];
+    t8 = r->n[8];
+
     t9 &= 0x03FFFFFUL;
     t1 += (x << 6);
 
@@ -266,11 +279,11 @@ SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
 }
 
 SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe_t *a) {
+    const uint32_t *t = a->n;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     secp256k1_fe_verify(a);
 #endif
-    const uint32_t *t = a->n;
     return (t[0] | t[1] | t[2] | t[3] | t[4] | t[5] | t[6] | t[7] | t[8] | t[9]) == 0;
 }
 
@@ -283,23 +296,25 @@ SECP256K1_INLINE static int secp256k1_fe_is_odd(const secp256k1_fe_t *a) {
 }
 
 SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe_t *a) {
+    int i;
 #ifdef VERIFY
     a->magnitude = 0;
     a->normalized = 1;
 #endif
-    for (int i=0; i<10; i++) {
+    for (i=0; i<10; i++) {
         a->n[i] = 0;
     }
 }
 
 static int secp256k1_fe_cmp_var(const secp256k1_fe_t *a, const secp256k1_fe_t *b) {
+    int i;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     VERIFY_CHECK(b->normalized);
     secp256k1_fe_verify(a);
     secp256k1_fe_verify(b);
 #endif
-    for (int i = 9; i >= 0; i--) {
+    for (i = 9; i >= 0; i--) {
         if (a->n[i] > b->n[i]) return 1;
         if (a->n[i] < b->n[i]) return -1;
     }
@@ -307,10 +322,12 @@ static int secp256k1_fe_cmp_var(const secp256k1_fe_t *a, const secp256k1_fe_t *b
 }
 
 static int secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
+    int i;
     r->n[0] = r->n[1] = r->n[2] = r->n[3] = r->n[4] = 0;
     r->n[5] = r->n[6] = r->n[7] = r->n[8] = r->n[9] = 0;
-    for (int i=0; i<32; i++) {
-        for (int j=0; j<4; j++) {
+    for (i=0; i<32; i++) {
+        int j;
+        for (j=0; j<4; j++) {
             int limb = (8*i+2*j)/26;
             int shift = (8*i+2*j)%26;
             r->n[limb] |= (uint32_t)((a[31-i] >> (2*j)) & 0x3) << shift;
@@ -329,13 +346,15 @@ static int secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
 
 /** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */
 static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe_t *a) {
+    int i;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     secp256k1_fe_verify(a);
 #endif
-    for (int i=0; i<32; i++) {
+    for (i=0; i<32; i++) {
+        int j;
         int c = 0;
-        for (int j=0; j<4; j++) {
+        for (j=0; j<4; j++) {
             int limb = (8*i+2*j)/26;
             int shift = (8*i+2*j)%26;
             c |= ((a->n[limb] >> shift) & 0x3) << (2 * j);
@@ -412,6 +431,11 @@ SECP256K1_INLINE static void secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1
 #endif
 
 SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t *a, const uint32_t * SECP256K1_RESTRICT b) {
+    uint64_t c, d;
+    uint64_t u0, u1, u2, u3, u4, u5, u6, u7, u8;
+    uint32_t t9, t1, t0, t2, t3, t4, t5, t6, t7;
+    const uint32_t M = 0x3FFFFFFUL, R0 = 0x3D10UL, R1 = 0x400UL;
+
     VERIFY_BITS(a[0], 30);
     VERIFY_BITS(a[1], 30);
     VERIFY_BITS(a[2], 30);
@@ -433,14 +457,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
     VERIFY_BITS(b[8], 30);
     VERIFY_BITS(b[9], 26);
 
-    const uint32_t M = 0x3FFFFFFUL, R0 = 0x3D10UL, R1 = 0x400UL;
     /** [... a b c] is a shorthand for ... + a<<52 + b<<26 + c<<0 mod n.
      *  px is a shorthand for sum(a[i]*b[x-i], i=0..x).
      *  Note that [x 0 0 0 0 0 0 0 0 0 0] = [x*R1 x*R0].
      */
 
-    uint64_t c, d;
-
     d  = (uint64_t)a[0] * b[9]
        + (uint64_t)a[1] * b[8]
        + (uint64_t)a[2] * b[7]
@@ -453,7 +474,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[0];
     /* VERIFY_BITS(d, 64); */
     /* [d 0 0 0 0 0 0 0 0 0] = [p9 0 0 0 0 0 0 0 0 0] */
-    uint32_t t9 = d & M; d >>= 26;
+    t9 = d & M; d >>= 26;
     VERIFY_BITS(t9, 26);
     VERIFY_BITS(d, 38);
     /* [d t9 0 0 0 0 0 0 0 0 0] = [p9 0 0 0 0 0 0 0 0 0] */
@@ -472,12 +493,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[1];
     VERIFY_BITS(d, 63);
     /* [d t9 0 0 0 0 0 0 0 0 c] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
-    uint64_t u0 = d & M; d >>= 26; c += u0 * R0;
+    u0 = d & M; d >>= 26; c += u0 * R0;
     VERIFY_BITS(u0, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 61);
     /* [d u0 t9 0 0 0 0 0 0 0 0 c-u0*R0] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
-    uint32_t t0 = c & M; c >>= 26; c += u0 * R1;
+    t0 = c & M; c >>= 26; c += u0 * R1;
     VERIFY_BITS(t0, 26);
     VERIFY_BITS(c, 37);
     /* [d u0 t9 0 0 0 0 0 0 0 c-u0*R1 t0-u0*R0] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
@@ -497,12 +518,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[2];
     VERIFY_BITS(d, 63);
     /* [d 0 t9 0 0 0 0 0 0 0 c t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
-    uint64_t u1 = d & M; d >>= 26; c += u1 * R0;
+    u1 = d & M; d >>= 26; c += u1 * R0;
     VERIFY_BITS(u1, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 63);
     /* [d u1 0 t9 0 0 0 0 0 0 0 c-u1*R0 t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
-    uint32_t t1 = c & M; c >>= 26; c += u1 * R1;
+    t1 = c & M; c >>= 26; c += u1 * R1;
     VERIFY_BITS(t1, 26);
     VERIFY_BITS(c, 38);
     /* [d u1 0 t9 0 0 0 0 0 0 c-u1*R1 t1-u1*R0 t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
@@ -522,12 +543,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[3];
     VERIFY_BITS(d, 63);
     /* [d 0 0 t9 0 0 0 0 0 0 c t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
-    uint64_t u2 = d & M; d >>= 26; c += u2 * R0;
+    u2 = d & M; d >>= 26; c += u2 * R0;
     VERIFY_BITS(u2, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 63);
     /* [d u2 0 0 t9 0 0 0 0 0 0 c-u2*R0 t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
-    uint32_t t2 = c & M; c >>= 26; c += u2 * R1;
+    t2 = c & M; c >>= 26; c += u2 * R1;
     VERIFY_BITS(t2, 26);
     VERIFY_BITS(c, 38);
     /* [d u2 0 0 t9 0 0 0 0 0 c-u2*R1 t2-u2*R0 t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
@@ -547,12 +568,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[4];
     VERIFY_BITS(d, 63);
     /* [d 0 0 0 t9 0 0 0 0 0 c t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
-    uint64_t u3 = d & M; d >>= 26; c += u3 * R0;
+    u3 = d & M; d >>= 26; c += u3 * R0;
     VERIFY_BITS(u3, 26);
     VERIFY_BITS(d, 37);
     /* VERIFY_BITS(c, 64); */
     /* [d u3 0 0 0 t9 0 0 0 0 0 c-u3*R0 t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
-    uint32_t t3 = c & M; c >>= 26; c += u3 * R1;
+    t3 = c & M; c >>= 26; c += u3 * R1;
     VERIFY_BITS(t3, 26);
     VERIFY_BITS(c, 39);
     /* [d u3 0 0 0 t9 0 0 0 0 c-u3*R1 t3-u3*R0 t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
@@ -572,12 +593,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[5];
     VERIFY_BITS(d, 62);
     /* [d 0 0 0 0 t9 0 0 0 0 c t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
-    uint64_t u4 = d & M; d >>= 26; c += u4 * R0;
+    u4 = d & M; d >>= 26; c += u4 * R0;
     VERIFY_BITS(u4, 26);
     VERIFY_BITS(d, 36);
     /* VERIFY_BITS(c, 64); */
     /* [d u4 0 0 0 0 t9 0 0 0 0 c-u4*R0 t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
-    uint32_t t4 = c & M; c >>= 26; c += u4 * R1;
+    t4 = c & M; c >>= 26; c += u4 * R1;
     VERIFY_BITS(t4, 26);
     VERIFY_BITS(c, 39);
     /* [d u4 0 0 0 0 t9 0 0 0 c-u4*R1 t4-u4*R0 t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
@@ -597,12 +618,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[6];
     VERIFY_BITS(d, 62);
     /* [d 0 0 0 0 0 t9 0 0 0 c t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
-    uint64_t u5 = d & M; d >>= 26; c += u5 * R0;
+    u5 = d & M; d >>= 26; c += u5 * R0;
     VERIFY_BITS(u5, 26);
     VERIFY_BITS(d, 36);
     /* VERIFY_BITS(c, 64); */
     /* [d u5 0 0 0 0 0 t9 0 0 0 c-u5*R0 t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
-    uint32_t t5 = c & M; c >>= 26; c += u5 * R1;
+    t5 = c & M; c >>= 26; c += u5 * R1;
     VERIFY_BITS(t5, 26);
     VERIFY_BITS(c, 39);
     /* [d u5 0 0 0 0 0 t9 0 0 c-u5*R1 t5-u5*R0 t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
@@ -622,12 +643,12 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[7];
     VERIFY_BITS(d, 61);
     /* [d 0 0 0 0 0 0 t9 0 0 c t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u6 = d & M; d >>= 26; c += u6 * R0;
+    u6 = d & M; d >>= 26; c += u6 * R0;
     VERIFY_BITS(u6, 26);
     VERIFY_BITS(d, 35);
     /* VERIFY_BITS(c, 64); */
     /* [d u6 0 0 0 0 0 0 t9 0 0 c-u6*R0 t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
-    uint32_t t6 = c & M; c >>= 26; c += u6 * R1;
+    t6 = c & M; c >>= 26; c += u6 * R1;
     VERIFY_BITS(t6, 26);
     VERIFY_BITS(c, 39);
     /* [d u6 0 0 0 0 0 0 t9 0 c-u6*R1 t6-u6*R0 t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
@@ -648,13 +669,13 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[9] * b[8];
     VERIFY_BITS(d, 58);
     /* [d 0 0 0 0 0 0 0 t9 0 c t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u7 = d & M; d >>= 26; c += u7 * R0;
+    u7 = d & M; d >>= 26; c += u7 * R0;
     VERIFY_BITS(u7, 26);
     VERIFY_BITS(d, 32);
     /* VERIFY_BITS(c, 64); */
     VERIFY_CHECK(c <= 0x800001703FFFC2F7ULL);
     /* [d u7 0 0 0 0 0 0 0 t9 0 c-u7*R0 t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint32_t t7 = c & M; c >>= 26; c += u7 * R1;
+    t7 = c & M; c >>= 26; c += u7 * R1;
     VERIFY_BITS(t7, 26);
     VERIFY_BITS(c, 38);
     /* [d u7 0 0 0 0 0 0 0 t9 c-u7*R1 t7-u7*R0 t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
@@ -675,7 +696,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
     d += (uint64_t)a[9] * b[9];
     VERIFY_BITS(d, 57);
     /* [d 0 0 0 0 0 0 0 0 t9 c t7 t6 t5 t4 t3 t2 t1 t0] = [p18 p17 p16 p15 p14 p13 p12 p11 p10 p9 p8 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u8 = d & M; d >>= 26; c += u8 * R0;
+    u8 = d & M; d >>= 26; c += u8 * R0;
     VERIFY_BITS(u8, 26);
     VERIFY_BITS(d, 31);
     /* VERIFY_BITS(c, 64); */
@@ -739,6 +760,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t
 }
 
 SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t *a) {
+    uint64_t c, d;
+    uint64_t u0, u1, u2, u3, u4, u5, u6, u7, u8;
+    uint32_t t9, t0, t1, t2, t3, t4, t5, t6, t7;
+    const uint32_t M = 0x3FFFFFFUL, R0 = 0x3D10UL, R1 = 0x400UL;
+
     VERIFY_BITS(a[0], 30);
     VERIFY_BITS(a[1], 30);
     VERIFY_BITS(a[2], 30);
@@ -750,14 +776,11 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
     VERIFY_BITS(a[8], 30);
     VERIFY_BITS(a[9], 26);
 
-    const uint32_t M = 0x3FFFFFFUL, R0 = 0x3D10UL, R1 = 0x400UL;
     /** [... a b c] is a shorthand for ... + a<<52 + b<<26 + c<<0 mod n.
      *  px is a shorthand for sum(a[i]*a[x-i], i=0..x).
      *  Note that [x 0 0 0 0 0 0 0 0 0 0] = [x*R1 x*R0].
      */
 
-    uint64_t c, d;
-
     d  = (uint64_t)(a[0]*2) * a[9]
        + (uint64_t)(a[1]*2) * a[8]
        + (uint64_t)(a[2]*2) * a[7]
@@ -765,7 +788,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)(a[4]*2) * a[5];
     /* VERIFY_BITS(d, 64); */
     /* [d 0 0 0 0 0 0 0 0 0] = [p9 0 0 0 0 0 0 0 0 0] */
-    uint32_t t9 = d & M; d >>= 26;
+    t9 = d & M; d >>= 26;
     VERIFY_BITS(t9, 26);
     VERIFY_BITS(d, 38);
     /* [d t9 0 0 0 0 0 0 0 0 0] = [p9 0 0 0 0 0 0 0 0 0] */
@@ -780,12 +803,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[5] * a[5];
     VERIFY_BITS(d, 63);
     /* [d t9 0 0 0 0 0 0 0 0 c] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
-    uint64_t u0 = d & M; d >>= 26; c += u0 * R0;
+    u0 = d & M; d >>= 26; c += u0 * R0;
     VERIFY_BITS(u0, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 61);
     /* [d u0 t9 0 0 0 0 0 0 0 0 c-u0*R0] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
-    uint32_t t0 = c & M; c >>= 26; c += u0 * R1;
+    t0 = c & M; c >>= 26; c += u0 * R1;
     VERIFY_BITS(t0, 26);
     VERIFY_BITS(c, 37);
     /* [d u0 t9 0 0 0 0 0 0 0 c-u0*R1 t0-u0*R0] = [p10 p9 0 0 0 0 0 0 0 0 p0] */
@@ -800,12 +823,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)(a[5]*2) * a[6];
     VERIFY_BITS(d, 63);
     /* [d 0 t9 0 0 0 0 0 0 0 c t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
-    uint64_t u1 = d & M; d >>= 26; c += u1 * R0;
+    u1 = d & M; d >>= 26; c += u1 * R0;
     VERIFY_BITS(u1, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 63);
     /* [d u1 0 t9 0 0 0 0 0 0 0 c-u1*R0 t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
-    uint32_t t1 = c & M; c >>= 26; c += u1 * R1;
+    t1 = c & M; c >>= 26; c += u1 * R1;
     VERIFY_BITS(t1, 26);
     VERIFY_BITS(c, 38);
     /* [d u1 0 t9 0 0 0 0 0 0 c-u1*R1 t1-u1*R0 t0] = [p11 p10 p9 0 0 0 0 0 0 0 p1 p0] */
@@ -821,12 +844,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[6] * a[6];
     VERIFY_BITS(d, 63);
     /* [d 0 0 t9 0 0 0 0 0 0 c t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
-    uint64_t u2 = d & M; d >>= 26; c += u2 * R0;
+    u2 = d & M; d >>= 26; c += u2 * R0;
     VERIFY_BITS(u2, 26);
     VERIFY_BITS(d, 37);
     VERIFY_BITS(c, 63);
     /* [d u2 0 0 t9 0 0 0 0 0 0 c-u2*R0 t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
-    uint32_t t2 = c & M; c >>= 26; c += u2 * R1;
+    t2 = c & M; c >>= 26; c += u2 * R1;
     VERIFY_BITS(t2, 26);
     VERIFY_BITS(c, 38);
     /* [d u2 0 0 t9 0 0 0 0 0 c-u2*R1 t2-u2*R0 t1 t0] = [p12 p11 p10 p9 0 0 0 0 0 0 p2 p1 p0] */
@@ -841,12 +864,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)(a[6]*2) * a[7];
     VERIFY_BITS(d, 63);
     /* [d 0 0 0 t9 0 0 0 0 0 c t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
-    uint64_t u3 = d & M; d >>= 26; c += u3 * R0;
+    u3 = d & M; d >>= 26; c += u3 * R0;
     VERIFY_BITS(u3, 26);
     VERIFY_BITS(d, 37);
     /* VERIFY_BITS(c, 64); */
     /* [d u3 0 0 0 t9 0 0 0 0 0 c-u3*R0 t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
-    uint32_t t3 = c & M; c >>= 26; c += u3 * R1;
+    t3 = c & M; c >>= 26; c += u3 * R1;
     VERIFY_BITS(t3, 26);
     VERIFY_BITS(c, 39);
     /* [d u3 0 0 0 t9 0 0 0 0 c-u3*R1 t3-u3*R0 t2 t1 t0] = [p13 p12 p11 p10 p9 0 0 0 0 0 p3 p2 p1 p0] */
@@ -862,12 +885,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[7] * a[7];
     VERIFY_BITS(d, 62);
     /* [d 0 0 0 0 t9 0 0 0 0 c t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
-    uint64_t u4 = d & M; d >>= 26; c += u4 * R0;
+    u4 = d & M; d >>= 26; c += u4 * R0;
     VERIFY_BITS(u4, 26);
     VERIFY_BITS(d, 36);
     /* VERIFY_BITS(c, 64); */
     /* [d u4 0 0 0 0 t9 0 0 0 0 c-u4*R0 t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
-    uint32_t t4 = c & M; c >>= 26; c += u4 * R1;
+    t4 = c & M; c >>= 26; c += u4 * R1;
     VERIFY_BITS(t4, 26);
     VERIFY_BITS(c, 39);
     /* [d u4 0 0 0 0 t9 0 0 0 c-u4*R1 t4-u4*R0 t3 t2 t1 t0] = [p14 p13 p12 p11 p10 p9 0 0 0 0 p4 p3 p2 p1 p0] */
@@ -882,12 +905,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)(a[7]*2) * a[8];
     VERIFY_BITS(d, 62);
     /* [d 0 0 0 0 0 t9 0 0 0 c t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
-    uint64_t u5 = d & M; d >>= 26; c += u5 * R0;
+    u5 = d & M; d >>= 26; c += u5 * R0;
     VERIFY_BITS(u5, 26);
     VERIFY_BITS(d, 36);
     /* VERIFY_BITS(c, 64); */
     /* [d u5 0 0 0 0 0 t9 0 0 0 c-u5*R0 t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
-    uint32_t t5 = c & M; c >>= 26; c += u5 * R1;
+    t5 = c & M; c >>= 26; c += u5 * R1;
     VERIFY_BITS(t5, 26);
     VERIFY_BITS(c, 39);
     /* [d u5 0 0 0 0 0 t9 0 0 c-u5*R1 t5-u5*R0 t4 t3 t2 t1 t0] = [p15 p14 p13 p12 p11 p10 p9 0 0 0 p5 p4 p3 p2 p1 p0] */
@@ -903,12 +926,12 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
        + (uint64_t)a[8] * a[8];
     VERIFY_BITS(d, 61);
     /* [d 0 0 0 0 0 0 t9 0 0 c t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u6 = d & M; d >>= 26; c += u6 * R0;
+    u6 = d & M; d >>= 26; c += u6 * R0;
     VERIFY_BITS(u6, 26);
     VERIFY_BITS(d, 35);
     /* VERIFY_BITS(c, 64); */
     /* [d u6 0 0 0 0 0 0 t9 0 0 c-u6*R0 t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
-    uint32_t t6 = c & M; c >>= 26; c += u6 * R1;
+    t6 = c & M; c >>= 26; c += u6 * R1;
     VERIFY_BITS(t6, 26);
     VERIFY_BITS(c, 39);
     /* [d u6 0 0 0 0 0 0 t9 0 c-u6*R1 t6-u6*R0 t5 t4 t3 t2 t1 t0] = [p16 p15 p14 p13 p12 p11 p10 p9 0 0 p6 p5 p4 p3 p2 p1 p0] */
@@ -924,13 +947,13 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
     d += (uint64_t)(a[8]*2) * a[9];
     VERIFY_BITS(d, 58);
     /* [d 0 0 0 0 0 0 0 t9 0 c t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u7 = d & M; d >>= 26; c += u7 * R0;
+    u7 = d & M; d >>= 26; c += u7 * R0;
     VERIFY_BITS(u7, 26);
     VERIFY_BITS(d, 32);
     /* VERIFY_BITS(c, 64); */
     VERIFY_CHECK(c <= 0x800001703FFFC2F7ULL);
     /* [d u7 0 0 0 0 0 0 0 t9 0 c-u7*R0 t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint32_t t7 = c & M; c >>= 26; c += u7 * R1;
+    t7 = c & M; c >>= 26; c += u7 * R1;
     VERIFY_BITS(t7, 26);
     VERIFY_BITS(c, 38);
     /* [d u7 0 0 0 0 0 0 0 t9 c-u7*R1 t7-u7*R0 t6 t5 t4 t3 t2 t1 t0] = [p17 p16 p15 p14 p13 p12 p11 p10 p9 0 p7 p6 p5 p4 p3 p2 p1 p0] */
@@ -947,7 +970,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
     d += (uint64_t)a[9] * a[9];
     VERIFY_BITS(d, 57);
     /* [d 0 0 0 0 0 0 0 0 t9 c t7 t6 t5 t4 t3 t2 t1 t0] = [p18 p17 p16 p15 p14 p13 p12 p11 p10 p9 p8 p7 p6 p5 p4 p3 p2 p1 p0] */
-    uint64_t u8 = d & M; d >>= 26; c += u8 * R0;
+    u8 = d & M; d >>= 26; c += u8 * R0;
     VERIFY_BITS(u8, 26);
     VERIFY_BITS(d, 31);
     /* VERIFY_BITS(c, 64); */
diff --git a/src/field_5x52_impl.h b/src/field_5x52_impl.h
index 748c0c07a5b3e..34b4d49c3495d 100644
--- a/src/field_5x52_impl.h
+++ b/src/field_5x52_impl.h
@@ -59,8 +59,8 @@ static void secp256k1_fe_normalize(secp256k1_fe_t *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
-    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
     uint64_t m;
+    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x1000003D1ULL;
@@ -126,8 +126,8 @@ static void secp256k1_fe_normalize_var(secp256k1_fe_t *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
-    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
     uint64_t m;
+    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x1000003D1ULL;
@@ -169,12 +169,12 @@ static void secp256k1_fe_normalize_var(secp256k1_fe_t *r) {
 static int secp256k1_fe_normalizes_to_zero(secp256k1_fe_t *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
-    /* Reduce t4 at the start so there will be at most a single carry from the first pass */
-    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
-
     /* z0 tracks a possible raw value of 0, z1 tracks a possible raw value of P */
     uint64_t z0, z1;
 
+    /* Reduce t4 at the start so there will be at most a single carry from the first pass */
+    uint64_t x = t4 >> 48; t4 &= 0x0FFFFFFFFFFFFULL;
+
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x1000003D1ULL;
     t1 += (t0 >> 52); t0 &= 0xFFFFFFFFFFFFFULL; z0  = t0; z1  = t0 ^ 0x1000003D0ULL;
@@ -190,22 +190,31 @@ static int secp256k1_fe_normalizes_to_zero(secp256k1_fe_t *r) {
 }
 
 static int secp256k1_fe_normalizes_to_zero_var(secp256k1_fe_t *r) {
-    uint64_t t0 = r->n[0], t4 = r->n[4];
+    uint64_t t0, t1, t2, t3, t4;
+    uint64_t z0, z1;
+    uint64_t x;
+
+    t0 = r->n[0];
+    t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
-    uint64_t x = t4 >> 48;
+    x = t4 >> 48;
 
     /* The first pass ensures the magnitude is 1, ... */
     t0 += x * 0x1000003D1ULL;
 
     /* z0 tracks a possible raw value of 0, z1 tracks a possible raw value of P */
-    uint64_t z0 = t0 & 0xFFFFFFFFFFFFFULL, z1 = z0 ^ 0x1000003D0ULL;
+    z0 = t0 & 0xFFFFFFFFFFFFFULL;
+    z1 = z0 ^ 0x1000003D0ULL;
 
     /* Fast return path should catch the majority of cases */
     if ((z0 != 0ULL) & (z1 != 0xFFFFFFFFFFFFFULL))
         return 0;
 
-    uint64_t t1 = r->n[1], t2 = r->n[2], t3 = r->n[3];
+    t1 = r->n[1];
+    t2 = r->n[2];
+    t3 = r->n[3];
+
     t4 &= 0x0FFFFFFFFFFFFULL;
 
     t1 += (t0 >> 52); t0  = z0;
@@ -231,11 +240,11 @@ SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
 }
 
 SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe_t *a) {
+    const uint64_t *t = a->n;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     secp256k1_fe_verify(a);
 #endif
-    const uint64_t *t = a->n;
     return (t[0] | t[1] | t[2] | t[3] | t[4]) == 0;
 }
 
@@ -248,23 +257,25 @@ SECP256K1_INLINE static int secp256k1_fe_is_odd(const secp256k1_fe_t *a) {
 }
 
 SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe_t *a) {
+    int i;
 #ifdef VERIFY
     a->magnitude = 0;
     a->normalized = 1;
 #endif
-    for (int i=0; i<5; i++) {
+    for (i=0; i<5; i++) {
         a->n[i] = 0;
     }
 }
 
 static int secp256k1_fe_cmp_var(const secp256k1_fe_t *a, const secp256k1_fe_t *b) {
+    int i;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     VERIFY_CHECK(b->normalized);
     secp256k1_fe_verify(a);
     secp256k1_fe_verify(b);
 #endif
-    for (int i = 4; i >= 0; i--) {
+    for (i = 4; i >= 0; i--) {
         if (a->n[i] > b->n[i]) return 1;
         if (a->n[i] < b->n[i]) return -1;
     }
@@ -272,9 +283,11 @@ static int secp256k1_fe_cmp_var(const secp256k1_fe_t *a, const secp256k1_fe_t *b
 }
 
 static int secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
+    int i;
     r->n[0] = r->n[1] = r->n[2] = r->n[3] = r->n[4] = 0;
-    for (int i=0; i<32; i++) {
-        for (int j=0; j<2; j++) {
+    for (i=0; i<32; i++) {
+        int j;
+        for (j=0; j<2; j++) {
             int limb = (8*i+4*j)/52;
             int shift = (8*i+4*j)%52;
             r->n[limb] |= (uint64_t)((a[31-i] >> (4*j)) & 0xF) << shift;
@@ -293,13 +306,15 @@ static int secp256k1_fe_set_b32(secp256k1_fe_t *r, const unsigned char *a) {
 
 /** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */
 static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe_t *a) {
+    int i;
 #ifdef VERIFY
     VERIFY_CHECK(a->normalized);
     secp256k1_fe_verify(a);
 #endif
-    for (int i=0; i<32; i++) {
+    for (i=0; i<32; i++) {
+        int j;
         int c = 0;
-        for (int j=0; j<2; j++) {
+        for (j=0; j<2; j++) {
             int limb = (8*i+4*j)/52;
             int shift = (8*i+4*j)%52;
             c |= ((a->n[limb] >> shift) & 0xF) << (4 * j);
diff --git a/src/field_5x52_int128_impl.h b/src/field_5x52_int128_impl.h
index ec631833cfa1a..f458873dd5c2c 100644
--- a/src/field_5x52_int128_impl.h
+++ b/src/field_5x52_int128_impl.h
@@ -16,6 +16,11 @@
 #endif
 
 SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t *a, const uint64_t * SECP256K1_RESTRICT b) {
+    __int128 c, d;
+    uint64_t t3, t4, tx, u0;
+    uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
+    const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
+
     VERIFY_BITS(a[0], 56);
     VERIFY_BITS(a[1], 56);
     VERIFY_BITS(a[2], 56);
@@ -28,16 +33,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
     VERIFY_BITS(b[4], 52);
     VERIFY_CHECK(r != b);
 
-    const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
     /*  [... a b c] is a shorthand for ... + a<<104 + b<<52 + c<<0 mod n.
      *  px is a shorthand for sum(a[i]*b[x-i], i=0..x).
      *  Note that [x 0 0 0 0 0] = [x*R].
      */
 
-    uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
-
-    __int128 c, d;
-
     d  = (__int128)a0 * b[3]
        + (__int128)a1 * b[2]
        + (__int128)a2 * b[1]
@@ -51,7 +51,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
     VERIFY_BITS(d, 115);
     VERIFY_BITS(c, 60);
     /* [c 0 0 0 0 0 d 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
-    uint64_t t3 = d & M; d >>= 52;
+    t3 = d & M; d >>= 52;
     VERIFY_BITS(t3, 52);
     VERIFY_BITS(d, 63);
     /* [c 0 0 0 0 d t3 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
@@ -66,11 +66,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
     d += c * R;
     VERIFY_BITS(d, 116);
     /* [d t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
-    uint64_t t4 = d & M; d >>= 52;
+    t4 = d & M; d >>= 52;
     VERIFY_BITS(t4, 52);
     VERIFY_BITS(d, 64);
     /* [d t4 t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
-    uint64_t tx = (t4 >> 48); t4 &= (M >> 4);
+    tx = (t4 >> 48); t4 &= (M >> 4);
     VERIFY_BITS(tx, 4);
     VERIFY_BITS(t4, 48);
     /* [d t4+(tx<<48) t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
@@ -84,7 +84,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
        + (__int128)a4 * b[1];
     VERIFY_BITS(d, 115);
     /* [d t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
-    uint64_t u0 = d & M; d >>= 52;
+    u0 = d & M; d >>= 52;
     VERIFY_BITS(u0, 52);
     VERIFY_BITS(d, 63);
     /* [d u0 t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
@@ -153,22 +153,22 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
 }
 
 SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t *a) {
+    __int128 c, d;
+    uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
+    int64_t t3, t4, tx, u0;
+    const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
+
     VERIFY_BITS(a[0], 56);
     VERIFY_BITS(a[1], 56);
     VERIFY_BITS(a[2], 56);
     VERIFY_BITS(a[3], 56);
     VERIFY_BITS(a[4], 52);
 
-    const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
     /**  [... a b c] is a shorthand for ... + a<<104 + b<<52 + c<<0 mod n.
      *  px is a shorthand for sum(a[i]*a[x-i], i=0..x).
      *  Note that [x 0 0 0 0 0] = [x*R].
      */
 
-    __int128 c, d;
-
-    uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
-
     d  = (__int128)(a0*2) * a3
        + (__int128)(a1*2) * a2;
     VERIFY_BITS(d, 114);
@@ -180,7 +180,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
     VERIFY_BITS(d, 115);
     VERIFY_BITS(c, 60);
     /* [c 0 0 0 0 0 d 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
-    uint64_t t3 = d & M; d >>= 52;
+    t3 = d & M; d >>= 52;
     VERIFY_BITS(t3, 52);
     VERIFY_BITS(d, 63);
     /* [c 0 0 0 0 d t3 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
@@ -194,11 +194,11 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
     d += c * R;
     VERIFY_BITS(d, 116);
     /* [d t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
-    uint64_t t4 = d & M; d >>= 52;
+    t4 = d & M; d >>= 52;
     VERIFY_BITS(t4, 52);
     VERIFY_BITS(d, 64);
     /* [d t4 t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
-    uint64_t tx = (t4 >> 48); t4 &= (M >> 4);
+    tx = (t4 >> 48); t4 &= (M >> 4);
     VERIFY_BITS(tx, 4);
     VERIFY_BITS(t4, 48);
     /* [d t4+(tx<<48) t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
@@ -210,7 +210,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
        + (__int128)(a2*2) * a3;
     VERIFY_BITS(d, 114);
     /* [d t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
-    uint64_t u0 = d & M; d >>= 52;
+    u0 = d & M; d >>= 52;
     VERIFY_BITS(u0, 52);
     VERIFY_BITS(d, 62);
     /* [d u0 t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
diff --git a/src/field_impl.h b/src/field_impl.h
index 2d161c91fb46a..25c15a90fcebe 100644
--- a/src/field_impl.h
+++ b/src/field_impl.h
@@ -22,16 +22,18 @@
 #endif
 
 static void secp256k1_fe_get_hex(char *r, int *rlen, const secp256k1_fe_t *a) {
+    secp256k1_fe_t b;
+    int i;
+    unsigned char tmp[32];
     if (*rlen < 65) {
         *rlen = 65;
         return;
     }
     *rlen = 65;
-    unsigned char tmp[32];
-    secp256k1_fe_t b = *a;
+    b = *a;
     secp256k1_fe_normalize(&b);
     secp256k1_fe_get_b32(tmp, &b);
-    for (int i=0; i<32; i++) {
+    for (i=0; i<32; i++) {
         static const char *c = "0123456789ABCDEF";
         r[2*i]   = c[(tmp[i] >> 4) & 0xF];
         r[2*i+1] = c[(tmp[i]) & 0xF];
@@ -40,6 +42,7 @@ static void secp256k1_fe_get_hex(char *r, int *rlen, const secp256k1_fe_t *a) {
 }
 
 static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen) {
+    int i;
     unsigned char tmp[32] = {0};
     static const int cvt[256] = {0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
                                  0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
@@ -57,7 +60,7 @@ static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen) {
                                  0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
                                  0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
                                  0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0};
-    for (int i=0; i<32; i++) {
+    for (i=0; i<32; i++) {
         if (alen > i*2)
             tmp[32 - alen/2 + i] = (cvt[(unsigned char)a[2*i]] << 4) + cvt[(unsigned char)a[2*i+1]];
     }
@@ -72,62 +75,62 @@ SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe_t *a, cons
 }
 
 static int secp256k1_fe_sqrt_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
+    int j;
 
     /** The binary representation of (p + 1)/4 has 3 blocks of 1s, with lengths in
      *  { 2, 22, 223 }. Use an addition chain to calculate 2^n - 1 for each block:
      *  1, [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223]
      */
 
-    secp256k1_fe_t x2;
     secp256k1_fe_sqr(&x2, a);
     secp256k1_fe_mul(&x2, &x2, a);
 
-    secp256k1_fe_t x3;
     secp256k1_fe_sqr(&x3, &x2);
     secp256k1_fe_mul(&x3, &x3, a);
 
-    secp256k1_fe_t x6 = x3;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
+    x6 = x3;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
     secp256k1_fe_mul(&x6, &x6, &x3);
 
-    secp256k1_fe_t x9 = x6;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
+    x9 = x6;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
     secp256k1_fe_mul(&x9, &x9, &x3);
 
-    secp256k1_fe_t x11 = x9;
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
+    x11 = x9;
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
     secp256k1_fe_mul(&x11, &x11, &x2);
 
-    secp256k1_fe_t x22 = x11;
-    for (int j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
+    x22 = x11;
+    for (j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
     secp256k1_fe_mul(&x22, &x22, &x11);
 
-    secp256k1_fe_t x44 = x22;
-    for (int j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
+    x44 = x22;
+    for (j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
     secp256k1_fe_mul(&x44, &x44, &x22);
 
-    secp256k1_fe_t x88 = x44;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
+    x88 = x44;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
     secp256k1_fe_mul(&x88, &x88, &x44);
 
-    secp256k1_fe_t x176 = x88;
-    for (int j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
+    x176 = x88;
+    for (j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
     secp256k1_fe_mul(&x176, &x176, &x88);
 
-    secp256k1_fe_t x220 = x176;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
+    x220 = x176;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
     secp256k1_fe_mul(&x220, &x220, &x44);
 
-    secp256k1_fe_t x223 = x220;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
+    x223 = x220;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
     secp256k1_fe_mul(&x223, &x223, &x3);
 
     /* The final result is then assembled using a sliding window over the blocks. */
 
-    secp256k1_fe_t t1 = x223;
-    for (int j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
+    t1 = x223;
+    for (j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x22);
-    for (int j=0; j<6; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<6; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x2);
     secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_sqr(r, &t1);
@@ -139,66 +142,66 @@ static int secp256k1_fe_sqrt_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 }
 
 static void secp256k1_fe_inv(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
+    int j;
 
     /** The binary representation of (p - 2) has 5 blocks of 1s, with lengths in
      *  { 1, 2, 22, 223 }. Use an addition chain to calculate 2^n - 1 for each block:
      *  [1], [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223]
      */
 
-    secp256k1_fe_t x2;
     secp256k1_fe_sqr(&x2, a);
     secp256k1_fe_mul(&x2, &x2, a);
 
-    secp256k1_fe_t x3;
     secp256k1_fe_sqr(&x3, &x2);
     secp256k1_fe_mul(&x3, &x3, a);
 
-    secp256k1_fe_t x6 = x3;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
+    x6 = x3;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
     secp256k1_fe_mul(&x6, &x6, &x3);
 
-    secp256k1_fe_t x9 = x6;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
+    x9 = x6;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
     secp256k1_fe_mul(&x9, &x9, &x3);
 
-    secp256k1_fe_t x11 = x9;
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
+    x11 = x9;
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
     secp256k1_fe_mul(&x11, &x11, &x2);
 
-    secp256k1_fe_t x22 = x11;
-    for (int j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
+    x22 = x11;
+    for (j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
     secp256k1_fe_mul(&x22, &x22, &x11);
 
-    secp256k1_fe_t x44 = x22;
-    for (int j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
+    x44 = x22;
+    for (j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
     secp256k1_fe_mul(&x44, &x44, &x22);
 
-    secp256k1_fe_t x88 = x44;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
+    x88 = x44;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
     secp256k1_fe_mul(&x88, &x88, &x44);
 
-    secp256k1_fe_t x176 = x88;
-    for (int j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
+    x176 = x88;
+    for (j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
     secp256k1_fe_mul(&x176, &x176, &x88);
 
-    secp256k1_fe_t x220 = x176;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
+    x220 = x176;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
     secp256k1_fe_mul(&x220, &x220, &x44);
 
-    secp256k1_fe_t x223 = x220;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
+    x223 = x220;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
     secp256k1_fe_mul(&x223, &x223, &x3);
 
     /* The final result is then assembled using a sliding window over the blocks. */
 
-    secp256k1_fe_t t1 = x223;
-    for (int j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
+    t1 = x223;
+    for (j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x22);
-    for (int j=0; j<5; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<5; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, a);
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x2);
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(r, a, &t1);
 }
 
@@ -228,6 +231,8 @@ static void secp256k1_fe_inv_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 }
 
 static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t u;
+    size_t i;
     if (len < 1)
         return;
 
@@ -235,12 +240,12 @@ static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t *r, const secp25
 
     r[0] = a[0];
 
-    size_t i = 0;
+    i = 0;
     while (++i < len) {
         secp256k1_fe_mul(&r[i], &r[i - 1], &a[i]);
     }
 
-    secp256k1_fe_t u; secp256k1_fe_inv_var(&u, &r[--i]);
+    secp256k1_fe_inv_var(&u, &r[--i]);
 
     while (i > 0) {
         int j = i--;