diff --git a/.github/workflows/cpp.yml b/.github/workflows/cpp.yml
index 5151095..865259f 100644
--- a/.github/workflows/cpp.yml
+++ b/.github/workflows/cpp.yml
@@ -12,9 +12,9 @@ jobs:
       run: |
         sudo apt-get install -y scons
         sudo apt-get install -y cmake scons
-        wget https://github.com/google/googletest/archive/release-1.8.0.zip
-        unzip -q release-1.8.0.zip
-        cd googletest-release-1.8.0
+        wget https://github.com/google/googletest/archive/release-1.11.0.zip
+        unzip -q release-1.11.0.zip
+        cd googletest-release-1.11.0
         cmake .
         make
         sudo make install
diff --git a/ChangeLog b/ChangeLog
index e2f22db..de19a6b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2022-04-11 Tatsuhiko Kubo <cubicdaiya@gmail.com>
+
+	* bugfix: fixed invalid offset in unified format difference when difference is too large.
+
+	* 1.20 released
+
 2015-05-03 Tatsuhiko Kubo <cubicdaiya@gmail.com>
 
 	* added some minor changes.
diff --git a/dtl/Diff.hpp b/dtl/Diff.hpp
index cff05fe..8c9c774 100644
--- a/dtl/Diff.hpp
+++ b/dtl/Diff.hpp
@@ -67,6 +67,8 @@ namespace dtl {
         bool               editDistanceOnly;
         uniHunkVec         uniHunks;
         comparator         cmp;
+        long long          ox;
+        long long          oy;
     public :
         Diff () {}
         
@@ -260,7 +262,8 @@ namespace dtl {
             if (isHuge()) {
                 pathCordinates.reserve(MAX_CORDINATES_SIZE);
             }
-            
+            ox = 0;
+            oy = 0;
             long long p = -1;
             fp = new long long[M + N + 3];
             fill(&fp[0], &fp[M + N + 3], -1);
@@ -595,18 +598,18 @@ namespace dtl {
                 while(px_idx < v[i].x || py_idx < v[i].y) {
                     if (v[i].y - v[i].x > py_idx - px_idx) {
                         if (!wasSwapped()) {
-                            ses.addSequence(*y, 0, y_idx, SES_ADD);
+                            ses.addSequence(*y, 0, y_idx + oy, SES_ADD);
                         } else {
-                            ses.addSequence(*y, y_idx, 0, SES_DELETE);
+                            ses.addSequence(*y, y_idx + oy, 0, SES_DELETE);
                         }
                         ++y;
                         ++y_idx;
                         ++py_idx;
                     } else if (v[i].y - v[i].x < py_idx - px_idx) {
                         if (!wasSwapped()) {
-                            ses.addSequence(*x, x_idx, 0, SES_DELETE);
+                            ses.addSequence(*x, x_idx + ox, 0, SES_DELETE);
                         } else {
-                            ses.addSequence(*x, 0, x_idx, SES_ADD);
+                            ses.addSequence(*x, 0, x_idx + ox, SES_ADD);
                         }
                         ++x;
                         ++x_idx;
@@ -614,10 +617,10 @@ namespace dtl {
                     } else {
                         if (!wasSwapped()) {
                             lcs.addSequence(*x);
-                            ses.addSequence(*x, x_idx, y_idx, SES_COMMON);
+                            ses.addSequence(*x, x_idx + ox, y_idx + oy, SES_COMMON);
                         } else {
                             lcs.addSequence(*y);
-                            ses.addSequence(*y, y_idx, x_idx, SES_COMMON);
+                            ses.addSequence(*y, y_idx + oy, x_idx + ox, SES_COMMON);
                         }
                         ++x;
                         ++y;
@@ -658,6 +661,8 @@ namespace dtl {
                 fp = new long long[M + N + 3];
                 fill(&fp[0], &fp[M + N + 3], -1);
                 fill(path.begin(), path.end(), -1);
+                ox = x_idx - 1;
+                oy = y_idx - 1;
                 return false;
             }
             return true;
diff --git a/dtl/variables.hpp b/dtl/variables.hpp
index cbf5a54..6720ec8 100644
--- a/dtl/variables.hpp
+++ b/dtl/variables.hpp
@@ -63,7 +63,7 @@ namespace dtl {
     /**
      * version string
      */
-    const string version = "1.19";
+    const string version = "1.20";
 
     /**
      * type of edit for SES
diff --git a/test/Patchtest.cpp b/test/Patchtest.cpp
index 44c10f5..2e87cf3 100644
--- a/test/Patchtest.cpp
+++ b/test/Patchtest.cpp
@@ -35,6 +35,7 @@ protected :
         cases.push_back(createCase("abcdefq3wefarhgorequgho4euhfteowauhfwehogfewrquhoi23hroewhoahfotrhguoiewahrgqqabcdef",
                                    "3abcdef4976fd86ouofita67t85r876e5e746578tgliuhopoqqabcdef")); // 8
         cases.push_back(createCase("abcqqqeqqqccc", "abdqqqeqqqddd")); // 9
+        cases.push_back(createCase("aaaaaaaaaaaaa>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>aaaadsafabcaaaaaaaaaaaaaaaaaaewaaabdaaaaaabbb", "aaaaaaaaaaaaaaadasfdsafsadasdafbaaaaaaaaaaaaaaaaaeaaaaaaaaaae&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&saaabcaaaaaaccc")); // 10
     }
     
     void TearDown () {}
@@ -96,3 +97,8 @@ TEST_F (Patchtest, patch_test9) {
     ASSERT_EQ(cases[9].B, cases[9].diff.patch(cases[9].A));
     ASSERT_EQ(cases[9].B, cases[9].diff.uniPatch(cases[9].A));
 }
+
+TEST_F (Patchtest, patch_test10) {
+    ASSERT_EQ(cases[10].B, cases[10].diff.patch(cases[10].A));
+    ASSERT_EQ(cases[10].B, cases[10].diff.uniPatch(cases[10].A));
+}
diff --git a/test/SConstruct b/test/SConstruct
index c124166..37873dd 100644
--- a/test/SConstruct
+++ b/test/SConstruct
@@ -11,6 +11,7 @@ def path_chomp(path):
 env  = Environment(
     CPPFLAGS=['-Wall', '-O2'],
     CPPPATH=['..'],
+	CXXFLAGS="-std=c++11",
 )
 
 conf = Configure(env);