diff --git a/gfx/thebes/GLContext.cpp b/gfx/thebes/GLContext.cpp
index 7c976f234cb0..fbc2ba00d765 100644
--- a/gfx/thebes/GLContext.cpp
+++ b/gfx/thebes/GLContext.cpp
@@ -383,6 +383,7 @@ GLContext::InitWithPrefix(const char *prefix, PRBool trygl)
         mViewportStack.AppendElement(nsIntRect(v[0], v[1], v[2], v[3]));
 
         fGetIntegerv(LOCAL_GL_MAX_TEXTURE_SIZE, &mMaxTextureSize);
+        fGetIntegerv(LOCAL_GL_MAX_RENDERBUFFER_SIZE, &mMaxRenderbufferSize);
 
         UpdateActualFormat();
     }
@@ -702,6 +703,9 @@ BasicTextureImage::Resize(const nsIntSize& aSize)
 PRBool
 GLContext::ResizeOffscreenFBO(const gfxIntSize& aSize)
 {
+    if (!IsOffscreenSizeAllowed(aSize))
+        return PR_FALSE;
+
     MakeCurrent();
 
     bool alpha = mCreationFormat.alpha > 0;
diff --git a/gfx/thebes/GLContext.h b/gfx/thebes/GLContext.h
index 9e79a3f319c4..d1c16183c737 100644
--- a/gfx/thebes/GLContext.h
+++ b/gfx/thebes/GLContext.h
@@ -994,11 +994,18 @@ protected:
         return teximage.forget();
     }
 
+    bool IsOffscreenSizeAllowed(const gfxIntSize& aSize) const {
+        PRInt32 biggerDimension = NS_MAX(aSize.width, aSize.height);
+        PRInt32 maxAllowed = NS_MIN(mMaxRenderbufferSize, mMaxTextureSize);
+        return biggerDimension <= maxAllowed;
+    }
+
 protected:
     nsTArray<nsIntRect> mViewportStack;
     nsTArray<nsIntRect> mScissorStack;
 
     GLint mMaxTextureSize;
+    GLint mMaxRenderbufferSize;
 
 public: