--- a/dom/base/ResponsiveImageSelector.cpp
+++ b/dom/base/ResponsiveImageSelector.cpp
@@ -351,16 +351,21 @@ ResponsiveImageSelector::SelectImage(boo
   nsPresContext *pctx = shell ? shell->GetPresContext() : nullptr;
   nsCOMPtr<nsIURI> baseURI = mOwnerNode ? mOwnerNode->GetBaseURI() : nullptr;
 
   if (!pctx || !doc || !baseURI) {
     return oldBest != -1;
   }
 
   double displayDensity = pctx->CSSPixelsToDevPixels(1.0f);
+  double overrideDPPX = pctx->GetOverrideDPPX();
+
+  if (overrideDPPX > 0) {
+    displayDensity = overrideDPPX;
+  }
 
   // Per spec, "In a UA-specific manner, choose one image source"
   // - For now, select the lowest density greater than displayDensity, otherwise
   //   the greatest density available
 
   // If the list contains computed width candidates, compute the current
   // effective image width.
   double computedWidth = -1;