diff --git a/src/structs.h b/src/structs.h
index da5ed2e..04e21a1 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -2909,6 +2909,7 @@
     linenr_T	w_popup_lnum;	    // close popup if cursor not on this line
     colnr_T	w_popup_mincol;	    // close popup if cursor before this col
     colnr_T	w_popup_maxcol;	    // close popup if cursor after this col
+    int		w_popup_drag;	    // allow moving the popup with the mouse
 
 # if defined(FEAT_TIMERS)
     timer_T	*w_popup_timer;	    // timer for closing popup window