diff --git a/src/macros.h b/src/macros.h
index b719462..a7964d8 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -344,9 +344,11 @@
 
 // Give an error in curwin is a popup window and evaluate to TRUE.
 #ifdef FEAT_PROP_POPUP
+# define WIN_IS_POPUP(wp) ((wp)->w_popup_flags != 0)
 # define ERROR_IF_POPUP_WINDOW error_if_popup_window(FALSE)
 # define ERROR_IF_ANY_POPUP_WINDOW error_if_popup_window(TRUE)
 #else
+# define WIN_IS_POPUP(wp) 0
 # define ERROR_IF_POPUP_WINDOW 0
 # define ERROR_IF_ANY_POPUP_WINDOW 0
 #endif