--- a/src/cx/common.h	Tue Nov 12 17:34:04 2024 +0100
+++ b/src/cx/common.h	Mon Nov 18 22:05:42 2024 +0100
@@ -330,6 +330,9 @@
  * @return zero, if no overflow occurred and the result is correct, non-zero
  * otherwise
  */
+#if __cplusplus
+extern "C"
+#endif
 int cx_szmul_impl(size_t a, size_t b, size_t *result);
 
 #endif // cx_szmul