diff --git a/include/wx/filedlg.h b/include/wx/filedlg.h
index 37643f0c0e..678e47eba3 100644
--- a/include/wx/filedlg.h
+++ b/include/wx/filedlg.h
@@ -131,6 +131,13 @@ public:
     static wxString AppendExtension(const wxString &filePath,
                                     const wxString &extensionList);
 
+    // Set the filter index to match the given extension.
+    //
+    // This is always valid to call, even if the extension is empty or the
+    // filter list doesn't contain it, the function will just do nothing in
+    // these cases.
+    void SetFilterIndexFromExt(const wxString& ext);
+
 protected:
     wxString      m_message;
     wxString      m_dir;
diff --git a/src/common/fldlgcmn.cpp b/src/common/fldlgcmn.cpp
index 6b02055206..33f691b084 100644
--- a/src/common/fldlgcmn.cpp
+++ b/src/common/fldlgcmn.cpp
@@ -200,7 +200,12 @@ void wxFileDialogBase::SetPath(const wxString& path)
     wxString ext;
     wxFileName::SplitPath(path, &m_dir, &m_fileName, &ext);
     if ( !ext.empty() )
+    {
+        SetFilterIndexFromExt(ext);
+
         m_fileName << wxT('.') << ext;
+    }
+
     m_path = path;
 }
 
@@ -216,6 +221,30 @@ void wxFileDialogBase::SetFilename(const wxString& name)
     m_path = wxFileName(m_dir, m_fileName).GetFullPath();
 }
 
+void wxFileDialogBase::SetFilterIndexFromExt(const wxString& ext)
+{
+    // if filter is of form "All files (*)|*|..." set correct filter index
+    if ( !ext.empty() && m_wildCard.find(wxT('|')) != wxString::npos )
+    {
+        int filterIndex = -1;
+
+        wxArrayString descriptions, filters;
+        // don't care about errors, handled already by wxFileDialog
+        (void)wxParseCommonDialogsFilter(m_wildCard, descriptions, filters);
+        for (size_t n=0; n<filters.GetCount(); n++)
+        {
+            if (filters[n].Contains(ext))
+            {
+                filterIndex = n;
+                break;
+            }
+        }
+
+        if (filterIndex >= 0)
+            SetFilterIndex(filterIndex);
+    }
+}
+
 //----------------------------------------------------------------------------
 // wxFileDialog convenience functions
 //----------------------------------------------------------------------------
@@ -250,26 +279,7 @@ wxString wxFileSelector(const wxString& title,
                             defaultFileName, filter2,
                             flags, wxPoint(x, y));
 
-    // if filter is of form "All files (*)|*|..." set correct filter index
-    if ( !defaultExtension.empty() && filter2.find(wxT('|')) != wxString::npos )
-    {
-        int filterIndex = 0;
-
-        wxArrayString descriptions, filters;
-        // don't care about errors, handled already by wxFileDialog
-        (void)wxParseCommonDialogsFilter(filter2, descriptions, filters);
-        for (size_t n=0; n<filters.GetCount(); n++)
-        {
-            if (filters[n].Contains(defaultExtension))
-            {
-                filterIndex = n;
-                break;
-            }
-        }
-
-        if (filterIndex > 0)
-            fileDialog.SetFilterIndex(filterIndex);
-    }
+    fileDialog.SetFilterIndexFromExt(defaultExtension);
 
     wxString filename;
     if ( fileDialog.ShowModal() == wxID_OK )