diff --git a/src/fallback.h b/src/fallback.h
index b0680de05..f8b7d4977 100644
--- a/src/fallback.h
+++ b/src/fallback.h
@@ -199,6 +199,6 @@ int flock(int fd, int op);
 
 #endif
 
-#ifndef wcstod_l
+#ifndef HAVE_WCSTOD_L
 double wcstod_l(const wchar_t *enptr, wchar_t **endptr, locale_t loc);
 #endif