diff -r e7ee815b04bf -r feebdaa346e5 src/HOL/Library/Multiset.thy
--- a/src/HOL/Library/Multiset.thy	Sun Nov 15 07:17:05 2020 +0000
+++ b/src/HOL/Library/Multiset.thy	Sun Nov 15 07:17:06 2020 +0000
@@ -3534,11 +3534,17 @@
 
 text \<open>Quickcheck generators\<close>
 
-definition (in term_syntax)
+context
+  includes term_syntax
+begin
+
+definition
   msetify :: "'a::typerep list \<times> (unit \<Rightarrow> Code_Evaluation.term)
     \<Rightarrow> 'a multiset \<times> (unit \<Rightarrow> Code_Evaluation.term)" where
   [code_unfold]: "msetify xs = Code_Evaluation.valtermify mset {\<cdot>} xs"
 
+end
+
 instantiation multiset :: (random) random
 begin