diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index bdd66f2f8b..f93075d2a0 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -1511,12 +1511,20 @@ gtk_popover_measure (GtkWidget      *widget,
   GtkCssStyle *style;
   GtkBorder shadow_width;
 
-  if (for_size >= 0 && (POS_IS_VERTICAL (priv->position) == (orientation == GTK_ORIENTATION_HORIZONTAL)))
-    for_size -= tail_height;
-
   style = gtk_css_node_get_style (gtk_widget_get_css_node (GTK_WIDGET (priv->contents_widget)));
   gtk_css_shadow_value_get_extents (style->used->box_shadow, &shadow_width);
 
+  if (for_size >= 0)
+    {
+      if ((POS_IS_VERTICAL (priv->position) == (orientation == GTK_ORIENTATION_HORIZONTAL)))
+        for_size -= tail_height;
+
+      if (orientation == GTK_ORIENTATION_HORIZONTAL)
+        for_size -= shadow_width.top + shadow_width.bottom;
+      else
+        for_size -= shadow_width.left + shadow_width.right;
+    }
+
   gtk_widget_measure (priv->contents_widget,
                       orientation, for_size,
                       minimum, natural,