diff --git a/src/picture.c b/src/picture.c
index 3f010e5..edb43d8 100644
--- a/src/picture.c
+++ b/src/picture.c
@@ -39,6 +39,7 @@
 
 #include <assert.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include <errno.h>