diff --git a/libsrc/colour/im_XYZ2Lab.c b/libsrc/colour/im_XYZ2Lab.c
index a52070c0..0646d94c 100644
--- a/libsrc/colour/im_XYZ2Lab.c
+++ b/libsrc/colour/im_XYZ2Lab.c
@@ -57,6 +57,7 @@
 #include <math.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
 
 #ifdef WITH_DMALLOC
 #include <dmalloc.h>