diff --git a/Makefile b/Makefile
index 6f0b440..f7d1f61 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 all:
-	gcc -D_POSIX_C_SOURCE -std=c11 -O3 -Wall -Werror -Wextra -Wshadow -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wvla -o gddr6 gddr6.c -lpci
+	gcc -std=c11 -O3 -Wall -Werror -Wextra -Wshadow -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wvla -o gddr6 gddr6.c -lpci
 clean:
 	rm -f gddr6
 install:
diff --git a/gddr6.c b/gddr6.c
index 42c8ef7..79a8a25 100644
--- a/gddr6.c
+++ b/gddr6.c
@@ -1,3 +1,5 @@
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -9,7 +11,6 @@
 #include <pci/pci.h>
 #include <signal.h>
 
-
 #define MAP_SIZE 0x1000
 #define PRINT_ERROR()                                        \
     do {                                                     \