--- a/xpcom/io/nsIFile.idl
+++ b/xpcom/io/nsIFile.idl
@@ -251,17 +251,19 @@ interface nsIFile : nsISupports
      *  native filesystem charset.
      *
      */
     readonly attribute AString target;
     [noscript] readonly attribute ACString nativeTarget;
     readonly attribute AString path;
     [notxpcom,nostdcall,must_use] PathString nativePath();
 %{C++
+#ifndef XP_WIN
     nsresult GetNativePath(nsACString& aPath);
+#endif
 %}
     /*
      * Returns a human-readable path string.
      * The result is deliberately quoted to prevent abuse.
      */
     [notxpcom,nostdcall,must_use] UTF8String displayPath();
 
     boolean exists();

--- a/xpcom/io/nsLocalFileWin.cpp
+++ b/xpcom/io/nsLocalFileWin.cpp
@@ -3553,23 +3553,16 @@ nsLocalFile::SetNativeLeafName(const nsA
 
 
 nsString
 nsLocalFile::NativePath()
 {
   return mWorkingPath;
 }
 
-nsresult
-nsIFile::GetNativePath(nsACString& aResult)
-{
-  //NS_WARNING("This API is lossy. Use GetPath !");
-  return NS_CopyUnicodeToNative(NativePath(), aResult);
-}
-
 nsCString
 nsLocalFile::DisplayPath()
 {
   nsAutoCString path('[');
   AppendUTF16toUTF8(mWorkingPath, path);
   path.Append(']');
   return path;
 }

--- a/xpcom/tests/gtest/TestFile.cpp
+++ b/xpcom/tests/gtest/TestFile.cpp
@@ -26,21 +26,22 @@ static already_AddRefed<nsIFile> NewFile
   nsCOMPtr<nsIFile> file =
     do_CreateInstance(NS_LOCAL_FILE_CONTRACTID, &rv);
   VerifyResult(rv, "Creating nsIFile");
   rv = file->InitWithFile(aBase);
   VerifyResult(rv, "InitWithFile");
   return file.forget();
 }
 
-static nsCString FixName(const char* aName)
+template <typename char_type>
+static nsTString<char_type> FixName(const char_type* aName)
 {
-  nsCString name;
+  nsTString<char_type> name;
   for (uint32_t i = 0; aName[i]; ++i) {
-    char ch = aName[i];
+    char_type ch = aName[i];
     // PR_GetPathSeparator returns the wrong value on Mac so don't use it
 #if defined(XP_WIN)
     if (ch == '/') {
       ch = '\\';
     }
 #endif
     name.Append(ch);
   }
@@ -374,32 +375,35 @@ static bool TestParent(nsIFile* aBase, n
 
 // Test nsIFile::Normalize and native path setting/getting
 static bool TestNormalizeNativePath(nsIFile* aBase, nsIFile* aStart)
 {
   nsCOMPtr<nsIFile> file = NewFile(aStart);
   if (!file)
     return false;
 
-  nsAutoCString path;
-  nsresult rv = file->GetNativePath(path);
-  VerifyResult(rv, "GetNativePath");
+  auto path = file->NativePath();
+#ifdef XP_WIN
+  path.Append(FixName(u"/./.."));
+  nsresult rv = file->InitWithPath(path);
+  VerifyResult(rv, "InitWithPath");
+#else
   path.Append(FixName("/./.."));
-  rv = file->InitWithNativePath(path);
+  nsresult rv = file->InitWithNativePath(path);
   VerifyResult(rv, "InitWithNativePath");
+#endif
   rv = file->Normalize();
   VerifyResult(rv, "Normalize");
-  rv = file->GetNativePath(path);
-  VerifyResult(rv, "GetNativePath (after normalization)");
+  path = file->NativePath();
 
-  nsAutoCString basePath;
-  rv = aBase->GetNativePath(basePath);
+  auto basePath = aBase->NativePath();
   VerifyResult(rv, "GetNativePath (base)");
 
-  EXPECT_TRUE(path.Equals(basePath)) << "Incorrect normalization: " << path.get() << " - " << basePath.get();
+  EXPECT_TRUE(path.Equals(basePath)) << "Incorrect normalization: " <<
+    file->DisplayPath().get() << " - " << aBase->DisplayPath().get();
   if (!path.Equals(basePath)) {
     return false;
   }
 
   return true;
 }
 
 TEST(TestFile, Tests)