diff -r 36c0fb2b60b2 -r f889ffd07c86 tests/test_string.c
--- a/tests/test_string.c	Sun Dec 28 17:31:20 2025 +0100
+++ b/tests/test_string.c	Sun Dec 28 18:30:25 2025 +0100
@@ -373,10 +373,19 @@
         cxstring result = cx_strchr(str, 'w');
         CX_TEST_ASSERT(result.length == 35);
         CX_TEST_ASSERT(0 == strcmp(result.ptr, "will find you - and I will kill you"));
+    }
+}
 
-        // just for coverage, call the _m variant
-        cxmutstr m = cx_strchr_m(cx_mutstrn(NULL, 0), 'a');
-        CX_TEST_ASSERT(0 == cx_strcmp(m, ""));
+CX_TEST(test_strchr_m) {
+    cxmutstr str = cx_mutstr((char*)"I will find you - and I will kill you");
+
+    CX_TEST_DO {
+        cxmutstr notfound = cx_strchr(str, 'x');
+        CX_TEST_ASSERT(notfound.length == 0);
+
+        cxmutstr result = cx_strchr(str, 'w');
+        CX_TEST_ASSERT(result.length == 35);
+        CX_TEST_ASSERT(0 == strcmp(result.ptr, "will find you - and I will kill you"));
     }
 }
 
@@ -397,10 +406,26 @@
 
         result = cx_strrchr(str, 'X');
         CX_TEST_ASSERT(0 == cx_strcmp(result, str));
+    }
+}
 
-        // just for coverage, call the _m variant
-        cxmutstr m = cx_strrchr_m(cx_mutstrn(NULL, 0), 'a');
-        CX_TEST_ASSERT(0 == cx_strcmp(m, ""));
+CX_TEST(test_strrchr_m) {
+    cxmutstr str = cx_mutstr((char*)"X will find you - and I will kill you");
+
+    CX_TEST_DO {
+        cxmutstr notfound = cx_strrchr(str, 'x');
+        CX_TEST_ASSERT(notfound.length == 0);
+
+        cxmutstr result = cx_strrchr(str, 'w');
+        CX_TEST_ASSERT(result.length == 13);
+        CX_TEST_ASSERT(0 == strcmp(result.ptr, "will kill you"));
+
+        result = cx_strrchr(str, 'u');
+        CX_TEST_ASSERT(result.length == 1);
+        CX_TEST_ASSERT(0 == strcmp(result.ptr, "u"));
+
+        result = cx_strrchr(str, 'X');
+        CX_TEST_ASSERT(0 == cx_strcmp(result, str));
     }
 }
 
@@ -1653,7 +1678,9 @@
     cx_test_register(suite, test_strsubs_c);
     cx_test_register(suite, test_strat);
     cx_test_register(suite, test_strchr);
+    cx_test_register(suite, test_strchr_m);
     cx_test_register(suite, test_strrchr);
+    cx_test_register(suite, test_strrchr_m);
     cx_test_register(suite, test_strstr);
     cx_test_register(suite, test_strcmp);
     cx_test_register(suite, test_strcasecmp);