--- a/src/ucx/szmul.c	Mon Feb 10 17:44:51 2025 +0100
+++ b/src/ucx/szmul.c	Sun Mar 02 18:10:52 2025 +0100
@@ -26,6 +26,9 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include "cx/common.h"
+
+#ifndef CX_SZMUL_BUILTIN
 int cx_szmul_impl(
         size_t a,
         size_t b,
@@ -43,4 +46,5 @@
         *result = 0;
         return 1;
     }
-}
\ No newline at end of file
+}
+#endif // CX_SZMUL_BUILTIN