--- a/src/ucx.c	Tue Jan 02 17:00:21 2018 +0100
+++ b/src/ucx.c	Sun Jan 21 10:13:21 2018 +0100
@@ -44,3 +44,20 @@
  */
 
 #include "ucx/ucx.h"
+
+#ifndef UCX_MUL_BUILTIN
+int ucx_szmul(size_t a, size_t b, size_t *result) {
+    if(a == 0 || b == 0) {
+        *result = 0;
+        return 1;
+    }
+    size_t r = a * b;
+    if(r / b == a) {
+        *result = r;
+        return 0;
+    } else {
+        *result = 0;
+        return 1;
+    }
+}
+#endif