diff --git a/src/kits/interface/Window.cpp b/src/kits/interface/Window.cpp
index 999a146fb2..fced7c64fc 100644
--- a/src/kits/interface/Window.cpp
+++ b/src/kits/interface/Window.cpp
@@ -582,6 +582,9 @@ BWindow::Minimize(bool minimize)
 	if (IsModal() || IsFloating() || fMinimized == minimize || !Lock())
 		return;
 
+	if (minimize && (Flags() & B_NOT_MINIMIZABLE) != 0)
+		return;
+
 	fMinimized = minimize;
 
 	fLink->StartMessage(AS_MINIMIZE_WINDOW);