diff --git a/src/mac/carbon/filedlg.cpp b/src/mac/carbon/filedlg.cpp
index 2c2004b9c4..3385b176a9 100644
--- a/src/mac/carbon/filedlg.cpp
+++ b/src/mac/carbon/filedlg.cpp
@@ -407,7 +407,8 @@ int wxFileDialog::ShowModal()
         dialogCreateOptions.optionFlags |= kNavDontAddTranslateItems;
 
         // The extension is important
-        dialogCreateOptions.optionFlags |= kNavPreserveSaveFileExtension;
+        if (numFilters < 2)
+            dialogCreateOptions.optionFlags |= kNavPreserveSaveFileExtension;
 
         err = ::NavCreatePutFileDialog(&dialogCreateOptions,
                                        // Suppresses the 'Default' (top) menu item