diff --git a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
index 7fea106b35be..7a32605ed641 100644
--- a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
+++ b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
@@ -197,6 +197,8 @@ NS_IMETHODIMP
 nsSVGForeignObjectFrame::PaintSVG(nsSVGRenderState *aContext,
                                   const nsIntRect *aDirtyRect)
 {
+  NS_ABORT_IF_FALSE(aDirtyRect, "We expect aDirtyRect to be non-null");
+
   if (IsDisabled())
     return NS_OK;
 
@@ -215,11 +217,9 @@ nsSVGForeignObjectFrame::PaintSVG(nsSVGRenderState *aContext,
   }
 
   /* Check if we need to draw anything. */
-  if (aDirtyRect) {
-    PRInt32 appUnitsPerDevPx = PresContext()->AppUnitsPerDevPixel();
-    if (!mRect.ToOutsidePixels(appUnitsPerDevPx).Intersects(*aDirtyRect))
-      return NS_OK;
-  }
+  PRInt32 appUnitsPerDevPx = PresContext()->AppUnitsPerDevPixel();
+  if (!mRect.ToOutsidePixels(appUnitsPerDevPx).Intersects(*aDirtyRect))
+    return NS_OK;
 
   gfxContext *gfx = aContext->GetGfxContext();