diff --git a/src/common/filename.cpp b/src/common/filename.cpp
index a57816daf0..13629a51af 100644
--- a/src/common/filename.cpp
+++ b/src/common/filename.cpp
@@ -2232,16 +2232,27 @@ wxString wxFileName::GetLongPath() const
             return pathOut;
         }
     }
+    else // GetLongPathName() failed.
+    {
+        // The error returned for non-existent UNC paths is different, to make
+        // things more interesting.
+        const DWORD err = ::GetLastError();
+        if ( err == ERROR_FILE_NOT_FOUND || err == ERROR_BAD_NETPATH )
+        {
+            // No need to try to do anything else, we're not going to be able
+            // to find a long path form of a non-existent path anyhow.
+            return path;
+        }
+    }
 
-    // Some other error occured.
+    // File exists, but some other error occurred.
     // We need to call FindFirstFile on each component in turn.
 
     WIN32_FIND_DATA findFileData;
     HANDLE hFind;
 
     if ( HasVolume() )
-        pathOut = GetVolume() +
-                  GetVolumeSeparator(wxPATH_DOS) +
+        pathOut = wxGetVolumeString(GetVolume(), wxPATH_DOS) +
                   GetPathSeparator(wxPATH_DOS);
     else
         pathOut.clear();
diff --git a/tests/filename/filenametest.cpp b/tests/filename/filenametest.cpp
index 03ab862a3e..4bc97850b5 100644
--- a/tests/filename/filenametest.cpp
+++ b/tests/filename/filenametest.cpp
@@ -545,15 +545,29 @@ TEST_CASE("wxFileName::ShortLongPath", "[filename]")
 
 #endif // __WINDOWS__
 
+// Small helper to make things slightly less verbose in the tests below.
+static wxString GetDOSPath(const wxFileName& fn)
+{
+    return fn.GetPath(wxPATH_NO_SEPARATOR, wxPATH_DOS);
+}
+
 TEST_CASE("wxFileName::UNC", "[filename]")
 {
     wxFileName fn("//share/path/name.ext", wxPATH_DOS);
     CHECK( fn.GetVolume() == "\\\\share" );
-    CHECK( fn.GetPath(wxPATH_NO_SEPARATOR, wxPATH_DOS) == "\\path" );
+    CHECK( GetDOSPath(fn) == "\\path" );
 
     fn.Assign("\\\\share2\\path2\\name.ext", wxPATH_DOS);
     CHECK( fn.GetVolume() == "\\\\share2" );
-    CHECK( fn.GetPath(wxPATH_NO_SEPARATOR, wxPATH_DOS) == "\\path2" );
+    CHECK( GetDOSPath(fn) == "\\path2" );
+
+    fn.SetPath("\\\\server\\volume\\path", wxPATH_DOS);
+    fn.AppendDir("subdir");
+    CHECK( fn.GetFullPath(wxPATH_DOS) == "\\\\server\\volume\\path\\subdir\\name.ext" );
+
+    // Check for a bug with normalization breaking the path (#22275).
+    fn.Normalize(wxPATH_NORM_LONG);
+    CHECK( fn.GetFullPath(wxPATH_DOS) == "\\\\server\\volume\\path\\subdir\\name.ext" );
 
 #ifdef __WINDOWS__
     // Check that doubled backslashes in the beginning of the path are not
@@ -574,13 +588,13 @@ TEST_CASE("wxFileName::VolumeUniqueName", "[filename]")
     wxFileName fn("\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}\\",
                   wxPATH_DOS);
     CHECK( fn.GetVolume() == "\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}" );
-    CHECK( fn.GetPath(wxPATH_NO_SEPARATOR, wxPATH_DOS) == "\\" );
+    CHECK( GetDOSPath(fn) == "\\" );
     CHECK( fn.GetFullPath(wxPATH_DOS) == "\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}\\" );
 
     fn.Assign("\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}\\"
               "Program Files\\setup.exe", wxPATH_DOS);
     CHECK( fn.GetVolume() == "\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}" );
-    CHECK( fn.GetPath(wxPATH_NO_SEPARATOR, wxPATH_DOS) == "\\Program Files" );
+    CHECK( GetDOSPath(fn) == "\\Program Files" );
     CHECK( fn.GetFullPath(wxPATH_DOS) == "\\\\?\\Volume{8089d7d7-d0ac-11db-9dd0-806d6172696f}\\Program Files\\setup.exe" );
 }