diff --git a/gfx/layers/d3d10/LayerManagerD3D10.cpp b/gfx/layers/d3d10/LayerManagerD3D10.cpp
index f5d37eecdf6..a880bd9ad7f 100644
--- a/gfx/layers/d3d10/LayerManagerD3D10.cpp
+++ b/gfx/layers/d3d10/LayerManagerD3D10.cpp
@@ -116,12 +116,6 @@ LayerManagerD3D10::~LayerManagerD3D10()
   Destroy();
 }
 
-static bool
-IsOptimus()
-{
-  return GetModuleHandleA("nvumdshim.dll");
-}
-
 bool
 LayerManagerD3D10::Initialize()
 {
@@ -254,7 +248,7 @@ LayerManagerD3D10::Initialize()
   // is broken on optimus devices. As a temporary solution we don't set it
   // there, the only way of reliably detecting we're on optimus is looking for
   // the DLL. See Bug 623807.
-  if (IsOptimus()) {
+  if (gfxWindowsPlatform::IsOptimus()) {
     swapDesc.Flags = 0;
   } else {
     swapDesc.Flags = DXGI_SWAP_CHAIN_FLAG_GDI_COMPATIBLE;
@@ -536,7 +530,7 @@ LayerManagerD3D10::VerifyBufferSize()
   }
 
   mRTView = nsnull;
-  if (IsOptimus()) {
+  if (gfxWindowsPlatform::IsOptimus()) {
     mSwapChain->ResizeBuffers(1, rect.width, rect.height,
                               DXGI_FORMAT_B8G8R8A8_UNORM,
                               0);
diff --git a/gfx/thebes/gfxWindowsPlatform.cpp b/gfx/thebes/gfxWindowsPlatform.cpp
index eda8a2be619..eb9217904ed 100644
--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -825,3 +825,9 @@ gfxWindowsPlatform::FontsPrefsChanged(nsIPrefBranch *aPrefBranch, const char *aP
         gfxTextRunWordCache::Flush();
     }
 }
+
+bool
+gfxWindowsPlatform::IsOptimus()
+{
+  return GetModuleHandleA("nvumdshim.dll");
+}
diff --git a/gfx/thebes/gfxWindowsPlatform.h b/gfx/thebes/gfxWindowsPlatform.h
index 6cf741e64aa..e92c14bd1ff 100644
--- a/gfx/thebes/gfxWindowsPlatform.h
+++ b/gfx/thebes/gfxWindowsPlatform.h
@@ -255,6 +255,8 @@ public:
     FT_Library GetFTLibrary();
 #endif
 
+    static bool IsOptimus();
+
 protected:
     RenderMode mRenderMode;