diff --git a/GNUmakefile b/GNUmakefile
index 7fe82fc7..dc01caaf 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -42,6 +42,7 @@ $(error Unexpected host platform $(UNAME_S).)
 endif
 
 CFLAGS += \
+	-std=gnu11 \
 	-Wall \
 	-Wextra \
 	-Wno-unused-parameter \