diff --git a/src/option.c b/src/option.c
index dd44fe4..535213c 100644
--- a/src/option.c
+++ b/src/option.c
@@ -1306,9 +1306,10 @@
 	    // remember character after option name
 	    afterchar = arg[len];
 
-	    // skip white space, allow ":set ai  ?"
-	    while (VIM_ISWHITE(arg[len]))
-		++len;
+	    if (!in_vim9script())
+		// skip white space, allow ":set ai  ?", ":set hlsearch  !"
+		while (VIM_ISWHITE(arg[len]))
+		    ++len;
 
 	    adding = FALSE;
 	    prepending = FALSE;
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 4b0ab2b..1584f17 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -3937,6 +3937,26 @@
   delfunc g:FuncA
 enddef
 
+def Test_option_modifier()
+  var lines =<< trim END
+      set hlsearch &  hlsearch  !
+      call assert_equal(1, &hlsearch)
+  END
+  CheckScriptSuccess(lines)
+
+  lines =<< trim END
+      vim9script
+      set hlsearch &
+  END
+  CheckScriptFailure(lines, 'E518:')
+
+  lines =<< trim END
+      vim9script
+      set hlsearch &  hlsearch  !
+  END
+  CheckScriptFailure(lines, 'E518:')
+enddef
+
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
   new
diff --git a/src/version.c b/src/version.c
index d1201f4..d217fe6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3021,
+/**/
     3020,
 /**/
     3019,