diff --git a/widget/cocoa/nsDragService.mm b/widget/cocoa/nsDragService.mm
index db45dd24187..8c3902bf847 100644
--- a/widget/cocoa/nsDragService.mm
+++ b/widget/cocoa/nsDragService.mm
@@ -140,19 +140,19 @@ nsDragService::ConstructDragImage(nsIDOMNode* aDOMNode,
   screenPoint.y = nsCocoaUtils::FlippedScreenY(screenPoint.y);
 
   CGFloat scaleFactor = nsCocoaUtils::GetBackingScaleFactor(gLastDragView);
-  nsIntPoint pt =
-    nsCocoaUtils::CocoaPointsToDevPixels(NSMakePoint(screenPoint.x,
-                                                     screenPoint.y),
-                                         scaleFactor);
 
   nsRefPtr<gfxASurface> surface;
   nsPresContext* pc;
-  nsresult rv = DrawDrag(aDOMNode, aRegion, pt.x, pt.y,
+  nsresult rv = DrawDrag(aDOMNode, aRegion,
+                         NSToIntRound(screenPoint.x),
+                         NSToIntRound(screenPoint.y),
                          aDragRect, getter_AddRefs(surface), &pc);
   if (!aDragRect->width || !aDragRect->height) {
     // just use some suitable defaults
     int32_t size = nsCocoaUtils::CocoaPointsToDevPixels(20, scaleFactor);
-    aDragRect->SetRect(pt.x, pt.y, size, size);
+    aDragRect->SetRect(nsCocoaUtils::CocoaPointsToDevPixels(screenPoint.x, scaleFactor),
+                       nsCocoaUtils::CocoaPointsToDevPixels(screenPoint.y, scaleFactor),
+                       size, size);
   }
 
   if (NS_FAILED(rv) || !surface)
diff --git a/widget/xpwidgets/nsBaseDragService.cpp b/widget/xpwidgets/nsBaseDragService.cpp
index 805d83f64ee..df2bb433365 100644
--- a/widget/xpwidgets/nsBaseDragService.cpp
+++ b/widget/xpwidgets/nsBaseDragService.cpp
@@ -450,6 +450,13 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
 
   *aPresContext = presShell->GetPresContext();
 
+  // convert mouse position to dev pixels of the prescontext
+  int32_t sx = aScreenX, sy = aScreenY;
+  ConvertToUnscaledDevPixels(*aPresContext, &sx, &sy);
+
+  aScreenDragRect->x = sx - mImageX;
+  aScreenDragRect->y = sy - mImageY;
+
   // check if drag images are disabled
   bool enableDragImages = Preferences::GetBool(DRAGIMAGES_PREF, true);
 
@@ -501,15 +508,15 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
   if (mImage) {
     nsCOMPtr<nsICanvasElementExternal> canvas = do_QueryInterface(dragNode);
     if (canvas) {
-      return DrawDragForImage(*aPresContext, nullptr, canvas, aScreenX,
-                              aScreenY, aScreenDragRect, aSurface);
+      return DrawDragForImage(*aPresContext, nullptr, canvas, sx, sy,
+                              aScreenDragRect, aSurface);
     }
 
     nsCOMPtr<nsIImageLoadingContent> imageLoader = do_QueryInterface(dragNode);
     // for image nodes, create the drag image from the actual image data
     if (imageLoader) {
-      return DrawDragForImage(*aPresContext, imageLoader, nullptr, aScreenX,
-                              aScreenY, aScreenDragRect, aSurface);
+      return DrawDragForImage(*aPresContext, imageLoader, nullptr, sx, sy,
+                              aScreenDragRect, aSurface);
     }
 
     // If the image is a popup, use that as the image. This allows custom drag
@@ -540,8 +547,8 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
   // if an image was specified, reposition the drag rectangle to
   // the supplied offset in mImageX and mImageY.
   if (mImage) {
-    aScreenDragRect->x = aScreenX - mImageX;
-    aScreenDragRect->y = aScreenY - mImageY;
+    aScreenDragRect->x = sx - mImageX;
+    aScreenDragRect->y = sy - mImageY;
   }
 
   *aSurface = surface;
diff --git a/widget/xpwidgets/nsBaseDragService.h b/widget/xpwidgets/nsBaseDragService.h
index cb00f8e3dbb..f6d2e896c15 100644
--- a/widget/xpwidgets/nsBaseDragService.h
+++ b/widget/xpwidgets/nsBaseDragService.h
@@ -61,11 +61,12 @@ protected:
    * that are relative to the upper-left corner of the window.
    *
    * aScreenX and aScreenY should be the screen coordinates of the mouse click
-   * for the drag.
+   * for the drag. These are in global display pixels.
    *
    * On return, aScreenDragRect will contain the screen coordinates of the
    * area being dragged. This is used by the platform-specific part of the
-   * drag service to determine the drag feedback.
+   * drag service to determine the drag feedback. This rect will be in the
+   * device pixels of the presContext.
    *
    * If there is no drag image, the returned surface will be null, but
    * aScreenDragRect will still be set to the drag area.