diff --git a/src/Gui/FileDialog.cpp b/src/Gui/FileDialog.cpp
index 4940447a84..45afbddf68 100644
--- a/src/Gui/FileDialog.cpp
+++ b/src/Gui/FileDialog.cpp
@@ -50,7 +50,7 @@
 
 using namespace Gui;
 
-namespace Gui {
+namespace {
 bool dontUseNativeDialog()
 {
 #if defined(USE_QT_FILEDIALOG)