diff --git a/src/Makefile.cfg b/src/Makefile.cfg
index 236d7ae2..78f52a67 100644
--- a/src/Makefile.cfg
+++ b/src/Makefile.cfg
@@ -122,6 +122,9 @@ endif
 ifndef GCC295
  WFLAGS+=-Wendif-labels
 endif
+ifdef GCC40
+ WFLAGS+=-std=gnu89
+endif
 ifdef GCC41
  WFLAGS+=-Wshadow
 endif