diff --git a/tools/sfnt2fnt.c b/tools/sfnt2fnt.c
index 2cbb7424f0..0ffe7e3a9b 100644
--- a/tools/sfnt2fnt.c
+++ b/tools/sfnt2fnt.c
@@ -23,6 +23,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef HAVE_FREETYPE