diff --git a/Makefile b/Makefile
index db49cec..cbf11ee 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 imcat: imcat.c
-	cc -std=c99 -Wall -g -o imcat imcat.c -lm
+	cc -D_POSIX_C_SOURCE=2 -std=c99 -Wall -g -o imcat imcat.c -lm
 
 run: imcat
 	./imcat ~/Desktop/*.png