diff --git a/src/errors.h b/src/errors.h
index 90aa292..965187f 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3306,3 +3306,7 @@
 EXTERN char e_invalid_argument_nr[]
 	INIT(= N_("E1291: Invalid argument: %ld"));
 #endif
+#ifdef FEAT_CMDWIN
+EXTERN char e_cmdline_window_already_open[]
+	INIT(= N_("E1292: Command-line window is already open"));
+#endif
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);
 	}
diff --git a/src/testdir/test_cmdwin.vim b/src/testdir/test_cmdwin.vim
index 45ecdd1..d641b29 100644
--- a/src/testdir/test_cmdwin.vim
+++ b/src/testdir/test_cmdwin.vim
@@ -356,5 +356,14 @@
   call assert_equal('', getcmdwintype())
 endfunc
 
+func Test_cant_open_cmdwin_in_cmdwin()
+  try
+    call feedkeys("q:q::q\<CR>", "x!")
+  catch
+    let caught = v:exception
+  endtry
+  call assert_match('E1292:', caught)
+endfunc
+
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index d7d0790..7534c23 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    64,
+/**/
     63,
 /**/
     62,