diff --git a/ttf.h b/ttf.h
index 457eee5..3ce3f31 100644
--- a/ttf.h
+++ b/ttf.h
@@ -11,6 +11,7 @@
 
 #ifndef TTF_H
 #  define TTF_H
+#  include <stddef.h>
 #  include <stdbool.h>
 #  include <sys/types.h>
 #  ifdef __cplusplus