diff --git a/rtengine/camconst.h b/rtengine/camconst.h
index fbc16cb13..0c0618671 100644
--- a/rtengine/camconst.h
+++ b/rtengine/camconst.h
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <map>
+#include <string>
 #include <vector>
 
 namespace Glib