diff --git a/src/common/filename.cpp b/src/common/filename.cpp
index 1d98b5c9be..0d6ed2f169 100644
--- a/src/common/filename.cpp
+++ b/src/common/filename.cpp
@@ -1784,15 +1784,27 @@ bool wxFileName::MakeRelativeTo(const wxString& pathBase, wxPathFormat format)
         m_dirs.Insert(wxT(".."), 0u);
     }
 
-    if ( format == wxPATH_UNIX || format == wxPATH_DOS )
+    switch ( GetFormat(format) )
     {
-        // a directory made relative with respect to itself is '.' under Unix
-        // and DOS, by definition (but we don't have to insert "./" for the
-        // files)
-        if ( m_dirs.IsEmpty() && IsDir() )
-        {
-            m_dirs.Add(wxT('.'));
-        }
+        case wxPATH_NATIVE:
+        case wxPATH_MAX:
+            wxFAIL_MSG( wxS("unreachable") );
+            wxFALLTHROUGH;
+
+        case wxPATH_UNIX:
+        case wxPATH_DOS:
+            // a directory made relative with respect to itself is '.' under
+            // Unix and DOS, by definition (but we don't have to insert "./"
+            // for the files)
+            if ( m_dirs.IsEmpty() && IsDir() )
+            {
+                m_dirs.Add(wxT('.'));
+            }
+            break;
+
+        case wxPATH_MAC:
+        case wxPATH_VMS:
+            break;
     }
 
     m_relative = true;
diff --git a/tests/filename/filenametest.cpp b/tests/filename/filenametest.cpp
index 9d4402a776..6e344126cd 100644
--- a/tests/filename/filenametest.cpp
+++ b/tests/filename/filenametest.cpp
@@ -133,6 +133,7 @@ private:
         CPPUNIT_TEST( TestSetPath );
         CPPUNIT_TEST( TestStrip );
         CPPUNIT_TEST( TestNormalize );
+        CPPUNIT_TEST( TestRelative );
         CPPUNIT_TEST( TestReplace );
         CPPUNIT_TEST( TestGetHumanReadable );
 #ifdef __WINDOWS__
@@ -158,6 +159,7 @@ private:
     void TestSplit();
     void TestSetPath();
     void TestStrip();
+    void TestRelative();
     void TestNormalize();
     void TestReplace();
     void TestGetHumanReadable();
@@ -441,6 +443,21 @@ void FileNameTestCase::TestNormalize()
 #endif // __WINDOWS__
 }
 
+void FileNameTestCase::TestRelative()
+{
+    wxFileName fn("a/b.cpp");
+    fn.MakeRelativeTo("a");
+    CPPUNIT_ASSERT_EQUAL( "b.cpp", fn.GetFullPath() );
+
+    fn.AssignDir("a/b");
+    fn.MakeRelativeTo("a");
+    CPPUNIT_ASSERT_EQUAL( "b/", fn.GetFullPath() );
+
+    fn.AssignDir("a");
+    fn.MakeRelativeTo("a");
+    CPPUNIT_ASSERT_EQUAL( "./", fn.GetFullPath() );
+}
+
 void FileNameTestCase::TestReplace()
 {
     static const struct FileNameTest