diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 2714fa1ccf..d67dd55b6e 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -74,6 +74,10 @@ def TestCompilingErrorInTry()
   delete('Xdir', 'rf')
 enddef
 
+def Test_comment_error()
+  v9.CheckDefFailure(['#{ comment'], 'E1170:')
+enddef
+
 def Test_compile_error_in_called_function()
   var lines =<< trim END
       vim9script
diff --git a/src/version.c b/src/version.c
index 507feaa49e..840a1eb672 100644
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    174,
 /**/
     173,
 /**/
diff --git a/src/vim9compile.c b/src/vim9compile.c
index c6316367e7..98fc84c58a 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2899,7 +2899,9 @@ compile_def_function(
 
 	if (*ea.cmd == '#')
 	{
-	    // "#" starts a comment
+	    // "#" starts a comment, but "#{" is an error
+	    if (vim9_bad_comment(ea.cmd))
+		goto erret;
 	    line = (char_u *)"";
 	    continue;
 	}