diff -r d80b2df54d31 -r a96320074298 src/HOL/Semiring_Normalization.thy
--- a/src/HOL/Semiring_Normalization.thy	Sun Jan 06 13:44:33 2019 +0100
+++ b/src/HOL/Semiring_Normalization.thy	Sun Jan 06 15:04:34 2019 +0100
@@ -67,7 +67,7 @@
 
 text \<open>Semiring normalization proper\<close>
 
-ML_file "Tools/semiring_normalizer.ML"
+ML_file \<open>Tools/semiring_normalizer.ML\<close>
 
 context comm_semiring_1
 begin