--- a/src/qtgui/recoll.h
+++ b/src/qtgui/recoll.h
@@ -22,6 +22,8 @@
 #include "rcldb.h"
 #include "ptmutex.h"
 
+#include <QString>
+
 // Misc declarations in need of sharing between the UI files
 
 // Open the database if needed. We now force a close/open by default
@@ -42,6 +44,8 @@
 extern int recollNeedsExit;
 extern void startManual(const string& helpindex);
 
+extern void applyStyleSheet(const QString&);
+
 #ifdef RCL_USE_ASPELL
 class Aspell;
 extern Aspell *aspell;