diff --git a/kstyle/breezestyle.cpp b/kstyle/breezestyle.cpp
--- a/kstyle/breezestyle.cpp
+++ b/kstyle/breezestyle.cpp
@@ -3162,8 +3162,12 @@
         if( !frameOption ) return true;
 
         // no frame for flat groupboxes
+        #if BREEZE_USE_KDE4
         QStyleOptionFrameV2 frameOption2( *frameOption );
         if( frameOption2.features & QStyleOptionFrameV2::Flat ) return true;
+        #else
+        if( frameOption->features & QStyleOptionFrame::Flat ) return true;
+        #endif
 
         // normal frame
         const auto& palette( option->palette );