diff --git a/gsk/gskroundedrect.c b/gsk/gskroundedrect.c
index f66dadf8e0e97aa444d2d8c6d110a211dfe17273..e852e014a1b4c193bd0682d90e65e72953ac9d64 100644
--- a/gsk/gskroundedrect.c
+++ b/gsk/gskroundedrect.c
@@ -1075,3 +1075,47 @@ gsk_rounded_rect_get_largest_cover (const GskRoundedRect  *self,
     *result = high;
 }
 
+/*< private >
+ * gsk_rounded_rect_corner_box_contains_point:
+ * @self: a rounded rectangle
+ * @corner: the corner
+ * @point: the point
+ *
+ * Returns whether @point is inside the rectangle defining
+ * the quarter ellipses of the given corner.
+ *
+ * Returns: true if @point is inside the @corner's box
+ */
+gboolean
+gsk_rounded_rect_corner_box_contains_point (const GskRoundedRect   *self,
+                                            GskCorner               corner,
+                                            const graphene_point_t *point)
+{
+  graphene_rect_t rect;
+
+  graphene_size_init_from_size (&rect.size, &self->corner[corner]);
+
+  switch (corner)
+    {
+    case GSK_CORNER_TOP_LEFT:
+      rect.origin.x = self->bounds.origin.x;
+      rect.origin.y = self->bounds.origin.y;
+      break;
+    case GSK_CORNER_TOP_RIGHT:
+      rect.origin.x = self->bounds.origin.x + self->bounds.size.width - self->corner[corner].width;
+      rect.origin.y = self->bounds.origin.y;
+      break;
+    case GSK_CORNER_BOTTOM_RIGHT:
+      rect.origin.x = self->bounds.origin.x + self->bounds.size.width - self->corner[corner].width;
+      rect.origin.y = self->bounds.origin.y + self->bounds.size.height - self->corner[corner].height;
+      break;
+    case GSK_CORNER_BOTTOM_LEFT:
+      rect.origin.x = self->bounds.origin.x;
+      rect.origin.y = self->bounds.origin.y + self->bounds.size.height - self->corner[corner].height;
+      break;
+    default:
+      g_assert_not_reached ();
+    }
+
+  return graphene_rect_contains_point (&rect, point);
+}
diff --git a/gsk/gskroundedrectprivate.h b/gsk/gskroundedrectprivate.h
index e83e1aed1c8d4a0e21660b08ebfc6e6d44ecd0a2..d9f5f56cce3e3a404ecb7c8c97149440d7804b57 100644
--- a/gsk/gskroundedrectprivate.h
+++ b/gsk/gskroundedrectprivate.h
@@ -75,6 +75,10 @@ GskRoundedRectIntersection gsk_rounded_rect_intersection          (const GskRoun
                                                                    const GskRoundedRect     *b,
                                                                    GskRoundedRect           *result);
 
+gboolean gsk_rounded_rect_corner_box_contains_point (const GskRoundedRect   *self,
+                                                     GskCorner               corner,
+                                                     const graphene_point_t *point);
+
 
 G_END_DECLS
 
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 38d288fe30a51b023ae95f974b83ffe5cb798311..0be15aff600d9ed63fc97325322659bc5f092960 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -70,6 +70,8 @@
 #include "gdk/gdktextureprivate.h"
 #include "gdk/gdktoplevelprivate.h"
 
+#include "gsk/gskroundedrectprivate.h"
+
 #include <cairo-gobject.h>
 #include <errno.h>
 #include <graphene.h>
@@ -1440,6 +1442,9 @@ get_edge_for_coordinates (GtkWindow *window,
   GtkCssBoxes css_boxes;
   const graphene_rect_t *border_rect;
   float left, top;
+  const GskRoundedRect *border;
+  graphene_point_t p;
+  int resize_handle_size;
 
 #define edge_or_minus_one(edge) ((supports_edge_constraints && (priv->edge_constraints & constraints_for_edge (edge)) != constraints_for_edge (edge)) ? -1 : edge)
 
@@ -1455,8 +1460,16 @@ get_edge_for_coordinates (GtkWindow *window,
     return -1;
 
   gtk_css_boxes_init (&css_boxes, GTK_WIDGET (window));
+  border = gtk_css_boxes_get_content_box (&css_boxes);
   border_rect = gtk_css_boxes_get_content_rect (&css_boxes);
 
+  resize_handle_size = RESIZE_HANDLE_CORNER_SIZE;
+  for (int i = 0 ; i < 4; i++)
+    {
+      resize_handle_size = MAX (resize_handle_size, border->corner[i].width);
+      resize_handle_size = MAX (resize_handle_size, border->corner[i].height);
+    }
+
   get_box_border (gtk_css_node_get_style (gtk_widget_get_css_node (GTK_WIDGET (window))),
                   &handle_size);
 
@@ -1478,10 +1491,10 @@ get_edge_for_coordinates (GtkWindow *window,
 
   if (x < left && x >= left - handle_size.left)
     {
-      if (y < top + RESIZE_HANDLE_CORNER_SIZE && y >= top - handle_size.top)
+      if (y < top + resize_handle_size && y >= top - handle_size.top)
         return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_WEST);
 
-      if (y > top + border_rect->size.height - RESIZE_HANDLE_CORNER_SIZE &&
+      if (y > top + border_rect->size.height - resize_handle_size &&
           y <= top + border_rect->size.height + handle_size.bottom)
         return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_WEST);
 
@@ -1490,10 +1503,10 @@ get_edge_for_coordinates (GtkWindow *window,
   else if (x > left + border_rect->size.width &&
            x <= left + border_rect->size.width + handle_size.right)
     {
-      if (y < top + RESIZE_HANDLE_CORNER_SIZE && y >= top - handle_size.top)
+      if (y < top + resize_handle_size  && y >= top - handle_size.top)
         return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_EAST);
 
-      if (y > top + border_rect->size.height - RESIZE_HANDLE_CORNER_SIZE &&
+      if (y > top + border_rect->size.height - resize_handle_size &&
           y <= top + border_rect->size.height + handle_size.bottom)
         return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_EAST);
 
@@ -1501,10 +1514,10 @@ get_edge_for_coordinates (GtkWindow *window,
     }
   else if (y < top && y >= top - handle_size.top)
     {
-      if (x < left + RESIZE_HANDLE_CORNER_SIZE && x >= left - handle_size.left)
+      if (x < left + resize_handle_size && x >= left - handle_size.left)
         return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_WEST);
 
-      if (x > left + border_rect->size.width - RESIZE_HANDLE_CORNER_SIZE &&
+      if (x > left + border_rect->size.width - resize_handle_size &&
           x <= left + border_rect->size.width + handle_size.right)
         return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_EAST);
 
@@ -1513,16 +1526,32 @@ get_edge_for_coordinates (GtkWindow *window,
   else if (y > top + border_rect->size.height &&
            y <= top + border_rect->size.height + handle_size.bottom)
     {
-      if (x < left + RESIZE_HANDLE_CORNER_SIZE && x >= left - handle_size.left)
+      if (x < left + resize_handle_size && x >= left - handle_size.left)
         return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_WEST);
 
-      if (x > left + border_rect->size.width - RESIZE_HANDLE_CORNER_SIZE &&
+      if (x > left + border_rect->size.width - resize_handle_size &&
           x <= left + border_rect->size.width + handle_size.right)
         return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_EAST);
 
       return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH);
     }
 
+  p = GRAPHENE_POINT_INIT (x,y );
+  if (!gsk_rounded_rect_contains_point (border, &p))
+    {
+      if (gsk_rounded_rect_corner_box_contains_point (border, GSK_CORNER_TOP_LEFT, &p))
+        return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_WEST);
+
+      if (gsk_rounded_rect_corner_box_contains_point (border, GSK_CORNER_TOP_RIGHT, &p))
+        return edge_or_minus_one (GDK_SURFACE_EDGE_NORTH_EAST);
+
+      if (gsk_rounded_rect_corner_box_contains_point (border, GSK_CORNER_BOTTOM_RIGHT, &p))
+        return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_EAST);
+
+      if (gsk_rounded_rect_corner_box_contains_point (border, GSK_CORNER_BOTTOM_LEFT, &p))
+        return edge_or_minus_one (GDK_SURFACE_EDGE_SOUTH_WEST);
+    }
+
   return -1;
 }