--- a/gfx/ipc/SharedDIBSurface.cpp
+++ b/gfx/ipc/SharedDIBSurface.cpp
@@ -37,17 +37,17 @@
 
 #include "SharedDIBSurface.h"
 
 #include "cairo.h"
 
 namespace mozilla {
 namespace gfx {
 
-static const cairo_user_data_key_t SHAREDDIB_KEY;
+static const cairo_user_data_key_t SHAREDDIB_KEY = {0};
 
 static const long kBytesPerPixel = 4;
 
 bool
 SharedDIBSurface::Create(HDC adc, PRUint32 aWidth, PRUint32 aHeight)
 {
   nsresult rv = mSharedDIB.Create(adc, aWidth, aHeight);
   if (NS_FAILED(rv) || !mSharedDIB.IsValid())

--- a/gfx/thebes/gfxSharedImageSurface.cpp
+++ b/gfx/thebes/gfxSharedImageSurface.cpp
@@ -39,17 +39,17 @@
 #include "base/basictypes.h"
 #include "gfxSharedImageSurface.h"
 #include "cairo.h"
 
 #define MOZ_ALIGN_WORD(x) (((x) + 3) & ~3)
 
 using mozilla::ipc::SharedMemory;
 
-static const cairo_user_data_key_t SHM_KEY;
+static const cairo_user_data_key_t SHM_KEY = {0};
 
 typedef struct _SharedImageInfo
 {
     PRInt32 width;
     PRInt32 height;
     PRInt32 format;
 } SharedImageInfo;