diff --git a/src/normal.c b/src/normal.c
index 72ebcd5..932d723 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -7147,6 +7147,11 @@
 #ifdef FEAT_CMDWIN
 	if (cap->nchar == ':' || cap->nchar == '/' || cap->nchar == '?')
 	{
+	    if (cmdwin_type != 0)
+	    {
+		emsg(_(e_cmdline_window_already_open));
+		return;
+	    }
 	    stuffcharReadbuff(cap->nchar);
 	    stuffcharReadbuff(K_CMDWIN);
 	}