diff --git a/package/frotz/frotz.mk b/package/frotz/frotz.mk
index 5af235137c..4c477c396d 100644
--- a/package/frotz/frotz.mk
+++ b/package/frotz/frotz.mk
@@ -21,7 +21,7 @@ endif
 define FROTZ_BUILD_CMDS
 	$(MAKE) -C $(@D) $(TARGET_CONFIGURE_OPTS) PREFIX=/usr CONFIG_DIR=/etc \
 		SOUND_TYPE=none CURSES="$(FROTZ_CURSES)" USE_UTF8=$(FROTZ_UTF8) \
-		CFLAGS="$(TARGET_CFLAGS) -std=c99"
+		CFLAGS="$(TARGET_CFLAGS) -std=gnu99"
 endef
 
 define FROTZ_INSTALL_TARGET_CMDS