diff --git a/grammar/src/toplevel.grm b/grammar/src/toplevel.grm
index 9cec344a502..9abe03d3600 100644
--- a/grammar/src/toplevel.grm
+++ b/grammar/src/toplevel.grm
@@ -3,7 +3,8 @@
   ;
 
 [start] script
-  : expression
+  : preamble expression*
+  ;
 
 preamble
   : namespaceHeader? import*