diff --git a/m-string.h b/m-string.h
index a86bbc3c..31157590 100644
--- a/m-string.h
+++ b/m-string.h
@@ -185,8 +185,17 @@ string_get_cstr(const string_t v)
 static inline void
 string_set (string_t v1, const string_t v2)
 {
+  STRING_CONTRACT (v1)
   STRING_CONTRACT (v2);
-  string_set_str (v1, string_get_cstr(v2));
+  size_t size = v2->size;
+  stringi_fit2size(v1, size+1);
+  if (v2->ptr != NULL) {
+    memcpy(v1->ptr, v2->ptr, size+1);
+  } else {
+    v1->ptr[0] = 0;
+  }
+  v1->size = size;
+  STRING_CONTRACT (v1);
 }
 
 static inline void