diff --git a/operations/common/matting-global.c b/operations/common/matting-global.c
index 802ce0a..652b4ac 100644
--- a/operations/common/matting-global.c
+++ b/operations/common/matting-global.c
@@ -19,6 +19,7 @@
 #include "config.h"
 #include <glib/gi18n-lib.h>
 #include <math.h>
+#include <stdlib.h>
 
 #ifdef GEGL_CHANT_PROPERTIES