diff --git a/c_runtime/bosatsu_ext_Bosatsu_l_Predef.c b/c_runtime/bosatsu_ext_Bosatsu_l_Predef.c
index 553099634..12c414497 100644
--- a/c_runtime/bosatsu_ext_Bosatsu_l_Predef.c
+++ b/c_runtime/bosatsu_ext_Bosatsu_l_Predef.c
@@ -182,7 +182,7 @@ BValue ___bsts_g_Bosatsu_l_Predef_l_partition__String(BValue a, BValue b) {
   // Some((x, y)) with x = a[0:offset], y = a[offset + b.len():]
   BValue x = bsts_string_substring(a, 0, offset);
   BValue y = bsts_string_substring_tail(a, offset + blen);
-  res = alloc_enum2(1, x, y);
+  res = alloc_enum1(1, alloc_struct2(x, y));
 
   done:
   release_value(a);
@@ -209,7 +209,7 @@ BValue ___bsts_g_Bosatsu_l_Predef_l_rpartition__String(BValue a, BValue b) {
   // Some((x, y)) with x = a[0:offset], y = a[offset + b.len():]
   BValue x = bsts_string_substring(a, 0, offset);
   BValue y = bsts_string_substring_tail(a, offset + blen);
-  res = alloc_enum2(1, x, y);
+  res = alloc_enum1(1, alloc_struct2(x, y));
 
   done:
   release_value(a);
diff --git a/c_runtime/bosatsu_runtime.c b/c_runtime/bosatsu_runtime.c
index b2f638b5a..78cb50461 100644
--- a/c_runtime/bosatsu_runtime.c
+++ b/c_runtime/bosatsu_runtime.c
@@ -578,7 +578,7 @@ int bsts_string_rfind(BValue haystack, BValue needle, int start) {
 
 
     // The maximum valid start index is haystack_len - needle_len
-    for (size_t i = (size_t)start; i <= 0; i--) {
+    for (size_t i = (size_t)start; 0 <= i; i--) {
         if (haystack_str->bytes[i] == needle_str->bytes[0]) {
             // Potential match found, check the rest of the needle
             size_t j;
diff --git a/test_workspace/Char.bosatsu b/test_workspace/Char.bosatsu
index 6a05d05ce..cb8fe407c 100644
--- a/test_workspace/Char.bosatsu
+++ b/test_workspace/Char.bosatsu
@@ -47,6 +47,15 @@ last_tests = TestSuite(
   ]
 )
 
+partition_tests = TestSuite("partition tests", [
+  Assertion("foo".partition_String("f") matches Some(("", "oo")), "foo partition_String f"),
+  Assertion("foo".partition_String("") matches None, "foo partition_String \"\""),
+  Assertion("foo".partition_String("x") matches None, "foo partition_String x"),
+  Assertion("foo".rpartition_String("o") matches Some(("fo", "")), "foo rpartition_String o"),
+  Assertion("foo".rpartition_String("") matches None, "foo rpartition_String \"\""),
+  Assertion("foo".rpartition_String("x") matches None, "foo rpartition_String x"),
+])
+
 match_tests = TestSuite("match tests",
   [
     Assertion("👋👋👋" matches "👋$.{_}👋", "test matching 1"),
@@ -84,5 +93,6 @@ tests = TestSuite("Char tests",
     last_tests,
     match_tests,
     glob_match_tests,
+    partition_tests,
   ]
 )
\ No newline at end of file