diff --git a/Makefile b/Makefile
index 13125d0..410666b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CC      := gcc
 LDFLAGS := -Wl,-O1,--sort-common,--as-needed
-CFLAGS  := -std=c99 -ffreestanding -Wall -Wextra
+CFLAGS  := -ffreestanding -Wall -Wextra
 
 prefix  := /usr/local
 
diff --git a/common.h b/common.h
index 51f87b1..9ca996d 100644
--- a/common.h
+++ b/common.h
@@ -1,9 +1,5 @@
 #pragma once
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-
 #include <stdlib.h>
 #include <stdint.h>