diff --git a/geo/src/utils.rs b/geo/src/utils.rs
index 96f74b330..0b7eb0a95 100644
--- a/geo/src/utils.rs
+++ b/geo/src/utils.rs
@@ -65,9 +65,26 @@ pub fn partial_max<T: PartialOrd>(a: T, b: T) -> T {
 
 // The Rust standard library has `min` for `Ord`, but not for `PartialOrd`
 pub fn partial_min<T: PartialOrd>(a: T, b: T) -> T {
-    if a > b {
+    if a < b {
         a
     } else {
         b
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::{partial_max, partial_min};
+
+    #[test]
+    fn test_partial_max() {
+        assert_eq!(5, partial_max(5, 4));
+        assert_eq!(5, partial_max(5, 5));
+    }
+
+    #[test]
+    fn test_partial_min() {
+        assert_eq!(4, partial_min(5, 4));
+        assert_eq!(4, partial_min(4, 4));
+    }
+}