diff --git a/plugins/messageviewerheaderplugins/grantleeheaderstyleplugin/grantleeheaderstyleinterface.cpp b/plugins/messageviewerheaderplugins/grantleeheaderstyleplugin/grantleeheaderstyleinterface.cpp
--- a/plugins/messageviewerheaderplugins/grantleeheaderstyleplugin/grantleeheaderstyleinterface.cpp
+++ b/plugins/messageviewerheaderplugins/grantleeheaderstyleplugin/grantleeheaderstyleinterface.cpp
@@ -32,6 +32,10 @@
 
 GrantleeHeaderStyleInterface::~GrantleeHeaderStyleInterface()
 {
+    if (mThemeManager) {
+        mThemeManager->setThemeMenu(nullptr);
+        mThemeManager->setActionGroup(nullptr);
+    }
 }
 
 void GrantleeHeaderStyleInterface::createAction(KActionMenu *menu, QActionGroup *actionGroup, KActionCollection *ac)