diff --git a/headers/os/interface/Window.h b/headers/os/interface/Window.h
index 3556d152eb..072ef913ed 100644
--- a/headers/os/interface/Window.h
+++ b/headers/os/interface/Window.h
@@ -203,7 +203,7 @@ public:
 											  float* minHeight, float* maxHeight);
 
 			status_t			SetDecoratorSettings(const BMessage& settings);
-			status_t			GetDecoratorSettings(BMessage* settings);
+			status_t			GetDecoratorSettings(BMessage* settings) const;
 
 			uint32				Workspaces() const;
 			void				SetWorkspaces(uint32);
diff --git a/src/kits/interface/Window.cpp b/src/kits/interface/Window.cpp
index a76ea04ae0..93f08c1ca0 100644
--- a/src/kits/interface/Window.cpp
+++ b/src/kits/interface/Window.cpp
@@ -1222,12 +1222,12 @@ BWindow::SetDecoratorSettings(const BMessage& settings)
 
 
 status_t
-BWindow::GetDecoratorSettings(BMessage* settings)
+BWindow::GetDecoratorSettings(BMessage* settings) const
 {
 	// read a flattened settings message from the app_server
 	// and put it into settings
 
-	if (!Lock())
+	if (!const_cast<BWindow*>(this)->Lock())
 		return B_ERROR;
 
 	status_t ret = fLink->StartMessage(AS_GET_DECORATOR_SETTINGS);
@@ -1251,7 +1251,7 @@ BWindow::GetDecoratorSettings(BMessage* settings)
 		}
 	}
 
-	Unlock();
+	const_cast<BWindow*>(this)->Unlock();
 
 	return ret;
 }