diff --git a/src/eval.c b/src/eval.c
index 1fd4765..020f557 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2860,7 +2860,8 @@
 	// "++" and "--" on the next line are a separate command.
 	p = eval_next_non_blank(*arg, evalarg, &getnext);
 	op = *p;
-	concat = op == '.' && (*(p + 1) == '.' || current_sctx.sc_version < 2);
+	concat = op == '.' && (*(p + 1) == '.'
+			      || (current_sctx.sc_version < 2 && !vim9script));
 	if ((op != '+' && op != '-' && !concat) || p[1] == '='
 					       || (p[1] == '.' && p[2] == '='))
 	    break;
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index 7ec43e9..49bb873 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -14,6 +14,7 @@
   END
   CheckScriptSuccess(lines)
   assert_fails('vim9cmd', 'E1164:')
+  assert_fails('vim9cmd echo "con" . "cat"', 'E15:')
 
   lines =<< trim END
       vim9script
diff --git a/src/version.c b/src/version.c
index b649014..a2a229b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3346,
+/**/
     3345,
 /**/
     3344,