diff --git a/library/stdlib_headers.h b/library/stdlib_headers.h
index 0b0155d..35d0dd0 100644
--- a/library/stdlib_headers.h
+++ b/library/stdlib_headers.h
@@ -189,6 +189,10 @@ extern BOOL NOCOMMON __lib_startup;
 
 /****************************************************************************/
 
+extern int __addition_overflows(ULONG x, ULONG y);
+
+/****************************************************************************/
+
 extern void NOCOMMON (*__alloca_trap)(void);
 
 /****************************************************************************/