diff --git a/src/string.c b/src/string.c
index 88575c7ca..768551d2d 100644
--- a/src/string.c
+++ b/src/string.c
@@ -1200,15 +1200,7 @@ mrb_str_cmp(mrb_state *mrb, mrb_value str1, mrb_value str2)
   mrb_int len1 = RSTR_LEN(s1);
   mrb_int len2 = RSTR_LEN(s2);
   mrb_int len = lesser(len1, len2);
-  mrb_int retval;
-
-  /* avoid UB: memcmp requires non-NULL pointers even when size is 0 */
-  if (len == 0) {
-    retval = 0;
-  }
-  else {
-    retval = memcmp(RSTR_PTR(s1), RSTR_PTR(s2), len);
-  }
+  mrb_int retval = (len == 0) ? 0 : memcmp(RSTR_PTR(s1), RSTR_PTR(s2), len);
 
   if (retval == 0) {
     if (len1 == len2) return 0;