diff --git a/src/window.c b/src/window.c
index 23037fe..964f1ef 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4431,6 +4431,11 @@
     frame_T	*nfr;
     frame_T	*foundfr;
 
+#ifdef FEAT_PROP_POPUP
+    if (popup_is_popup(wp))
+	// popups don't have neighbors.
+	return NULL;
+#endif
     foundfr = wp->w_frame;
     while (count--)
     {
@@ -4513,6 +4518,11 @@
     frame_T	*nfr;
     frame_T	*foundfr;
 
+#ifdef FEAT_PROP_POPUP
+    if (popup_is_popup(wp))
+	// popups don't have neighbors.
+	return NULL;
+#endif
     foundfr = wp->w_frame;
     while (count--)
     {