diff --git a/src/gtk/filedlg.cpp b/src/gtk/filedlg.cpp
index 6f3b775ada..1d13bb69df 100644
--- a/src/gtk/filedlg.cpp
+++ b/src/gtk/filedlg.cpp
@@ -268,11 +268,11 @@ bool wxFileDialog::Create(wxWindow *parent, const wxString& message,
     if ( !wildCard.empty() && !defaultFileName.empty() &&
             !wxFileName(defaultFileName).HasExt() )
     {
-        // append the default extension to the initial file name: GTK won't do
-        // it for us by default (unlike e.g. MSW)
-        const wxString defaultExt = m_fc.GetCurrentWildCard().AfterFirst('.');
-        if ( defaultExt.find_first_of("?*") == wxString::npos )
-            defaultFileNameWithExt += "." + defaultExt;
+        // append the default extension, if any, to the initial file name: GTK
+        // won't do it for us by default (unlike e.g. MSW)
+        const wxFileName fnWC(m_fc.GetCurrentWildCard());
+        if ( fnWC.HasExt() )
+            defaultFileNameWithExt << "." << fnWC.GetExt();
     }