--- a/dom/media/platforms/ffmpeg/ffvpx/FFVPXRuntimeLinker.cpp
+++ b/dom/media/platforms/ffmpeg/ffvpx/FFVPXRuntimeLinker.cpp
@@ -2,19 +2,23 @@
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "FFVPXRuntimeLinker.h"
 #include "FFmpegLibWrapper.h"
 #include "FFmpegLog.h"
-#include "nsIFile.h"
+#include "mozilla/FileUtils.h"
+#include "nsLocalFile.h"
 #include "prmem.h"
 #include "prlink.h"
+#ifdef XP_WIN
+#include <windows.h>
+#endif
 
 // We use a known symbol located in lgpllibs to determine its location.
 // soundtouch happens to be always included in lgpllibs
 #include "soundtouch/SoundTouch.h"
 
 namespace mozilla {
 
 template <int V> class FFmpegDecoderModule
@@ -24,83 +28,86 @@ public:
 };
 
 static FFmpegLibWrapper sFFVPXLib;
 
 FFVPXRuntimeLinker::LinkStatus FFVPXRuntimeLinker::sLinkStatus =
   LinkStatus_INIT;
 
 static PRLibrary*
-MozAVLink(const char* aName)
+MozAVLink(nsIFile* aFile)
 {
   PRLibSpec lspec;
+  PathString path = aFile->NativePath();
+#ifdef XP_WIN
+  lspec.type = PR_LibSpec_PathnameU;
+  lspec.value.pathname_u = path.get();
+#else
   lspec.type = PR_LibSpec_Pathname;
-  lspec.value.pathname = aName;
+  lspec.value.pathname = path.get();
+#endif
 #ifdef MOZ_WIDGET_ANDROID
   PRLibrary* lib = PR_LoadLibraryWithFlags(lspec, PR_LD_NOW | PR_LD_GLOBAL);
 #else
   PRLibrary* lib = PR_LoadLibraryWithFlags(lspec, PR_LD_NOW | PR_LD_LOCAL);
 #endif
   if (!lib) {
-    FFMPEG_LOG("unable to load library %s", aName);
+    FFMPEG_LOG("unable to load library %s", aFile->HumanReadablePath().get());
   }
   return lib;
 }
 
 /* static */ bool
 FFVPXRuntimeLinker::Init()
 {
   if (sLinkStatus) {
     return sLinkStatus == LinkStatus_SUCCEEDED;
   }
 
   sLinkStatus = LinkStatus_FAILED;
 
   // We retrieve the path of the lgpllibs library as this is where mozavcodec
   // and mozavutil libs are located.
-  char* lgpllibsname = PR_GetLibraryName(nullptr, "lgpllibs");
-  if (!lgpllibsname) {
+  PathString lgpllibsname = GetLibraryName(nullptr, "lgpllibs");
+  if (lgpllibsname.IsEmpty()) {
     return false;
   }
-  char* path =
-    PR_GetLibraryFilePathname(lgpllibsname,
-                              (PRFuncPtr)&soundtouch::SoundTouch::getVersionId);
-  PR_FreeLibraryName(lgpllibsname);
-  if (!path) {
+  PathString path =
+    GetLibraryFilePathname(lgpllibsname.get(),
+                           (PRFuncPtr)&soundtouch::SoundTouch::getVersionId);
+  if (path.IsEmpty()) {
     return false;
   }
-  nsCOMPtr<nsIFile> xulFile = do_CreateInstance(NS_LOCAL_FILE_CONTRACTID);
-  if (!xulFile ||
-      NS_FAILED(xulFile->InitWithNativePath(nsDependentCString(path)))) {
-    PR_Free(path); // PR_GetLibraryFilePathname() uses PR_Malloc().
+  RefPtr<nsLocalFile> xulFile = new nsLocalFile(path);
+  if (xulFile->NativePath().IsEmpty()) {
     return false;
   }
-  PR_Free(path); // PR_GetLibraryFilePathname() uses PR_Malloc().
 
   nsCOMPtr<nsIFile> rootDir;
   if (NS_FAILED(xulFile->GetParent(getter_AddRefs(rootDir))) || !rootDir) {
     return false;
   }
-  nsAutoCString rootPath;
-  if (NS_FAILED(rootDir->GetNativePath(rootPath))) {
+  PathString rootPath = rootDir->NativePath();
+
+  /* Get the platform-dependent library name of the module */
+  PathString libname = GetLibraryName(rootPath.get(), "mozavutil");
+  if (libname.IsEmpty()) {
     return false;
   }
-
-  char* libname = NULL;
-  /* Get the platform-dependent library name of the module */
-  libname = PR_GetLibraryName(rootPath.get(), "mozavutil");
-  if (!libname) {
+  RefPtr<nsLocalFile> libFile = new nsLocalFile(libname);
+  if (libFile->NativePath().IsEmpty()) {
     return false;
   }
-  sFFVPXLib.mAVUtilLib = MozAVLink(libname);
-  PR_FreeLibraryName(libname);
-  libname = PR_GetLibraryName(rootPath.get(), "mozavcodec");
-  if (libname) {
-    sFFVPXLib.mAVCodecLib = MozAVLink(libname);
-    PR_FreeLibraryName(libname);
+  sFFVPXLib.mAVUtilLib = MozAVLink(libFile);
+  libname = GetLibraryName(rootPath.get(), "mozavcodec");
+  if (!libname.IsEmpty()) {
+    libFile = new nsLocalFile(libname);
+    if (!libFile->NativePath().IsEmpty()) {
+      sFFVPXLib.mAVCodecLib = MozAVLink(libFile);
+    }
   }
   if (sFFVPXLib.Link() == FFmpegLibWrapper::LinkResult::Success) {
     sLinkStatus = LinkStatus_SUCCEEDED;
     return true;
   }
   return false;
 }