diff --git a/core/global.h b/core/global.h
index cfd5f0556..677039c32 100644
--- a/core/global.h
+++ b/core/global.h
@@ -7,6 +7,7 @@
 #ifndef OKULAR_GLOBAL_H
 #define OKULAR_GLOBAL_H
 
+#include <QFlags>
 #include <QGlobalStatic>
 
 /**