diff --git a/lib2geom/src/2geom/utils.h b/lib2geom/src/2geom/utils.h

index 5ab1917..538ef57 100644

--- a/lib2geom/src/2geom/utils.h

+++ b/lib2geom/src/2geom/utils.h

@@ -35,6 +35,7 @@

 #include <cmath>

 #include <vector>

+#include <stddef.h>

 namespace Geom {