diff --git a/gfx/thebes/gfxWindowsPlatform.cpp b/gfx/thebes/gfxWindowsPlatform.cpp
index c800d7ce770e..bac3b9615a6d 100644
--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -692,7 +692,7 @@ gfxWindowsPlatform::WindowsOSVersion()
 }
 
 void 
-gfxWindowsPlatform::GetDLLVersion(PRUnichar *aDLLPath, nsAString& aVersion)
+gfxWindowsPlatform::GetDLLVersion(const PRUnichar *aDLLPath, nsAString& aVersion)
 {
     DWORD versInfoSize, vers[4] = {0};
     // version info not available case
@@ -703,7 +703,7 @@ gfxWindowsPlatform::GetDLLVersion(PRUnichar *aDLLPath, nsAString& aVersion)
     if (!versionInfo.AppendElements(PRUint32(versInfoSize))) {
         return;
     }
-    if (!GetFileVersionInfoW(aDLLPath, NULL, versInfoSize, 
+    if (!GetFileVersionInfoW(aDLLPath, 0, versInfoSize, 
            LPBYTE(versionInfo.Elements()))) {
         return;
     } 
diff --git a/gfx/thebes/gfxWindowsPlatform.h b/gfx/thebes/gfxWindowsPlatform.h
index f963c24acdb5..cfc471cd887a 100644
--- a/gfx/thebes/gfxWindowsPlatform.h
+++ b/gfx/thebes/gfxWindowsPlatform.h
@@ -227,7 +227,7 @@ public:
 
     static PRInt32 WindowsOSVersion();
 
-    static void GetDLLVersion(PRUnichar *aDLLPath, nsAString& aVersion);
+    static void GetDLLVersion(const PRUnichar *aDLLPath, nsAString& aVersion);
 
     virtual void FontsPrefsChanged(nsIPrefBranch *aPrefBranch, const char *aPref);
 
diff --git a/widget/src/windows/GfxInfo.cpp b/widget/src/windows/GfxInfo.cpp
index 25da0324a8a3..3c575277230e 100644
--- a/widget/src/windows/GfxInfo.cpp
+++ b/widget/src/windows/GfxInfo.cpp
@@ -352,9 +352,9 @@ GfxInfo::Init()
     // with bad Intel driver installations where the DriverVersion reported by the registry was
     // not the version of the DLL.
     PRBool is64bitApp = sizeof(void*) == 8;
-    PRUnichar *dllFileName = is64bitApp
-                           ? L"igd10umd64.dll"
-                           : L"igd10umd32.dll";
+    const PRUnichar *dllFileName = is64bitApp
+                                 ? L"igd10umd64.dll"
+                                 : L"igd10umd32.dll";
     nsString dllVersion;
     // if GetDLLVersion fails, it gives "0.0.0.0"
     gfxWindowsPlatform::GetPlatform()->GetDLLVersion(dllFileName, dllVersion);