diff --git a/rtengine/ciecam02.h b/rtengine/ciecam02.h
index 5f5dd9bca..8b532fba0 100644
--- a/rtengine/ciecam02.h
+++ b/rtengine/ciecam02.h
@@ -19,6 +19,7 @@
 #pragma once
 
 #include <cmath>
+#include <cstdint>
 
 #include "opthelper.h"