diff -r 5b067c681989 -r b4b11391c676 src/HOL/Multivariate_Analysis/Derivative.thy
--- a/src/HOL/Multivariate_Analysis/Derivative.thy	Wed Dec 30 11:32:56 2015 +0100
+++ b/src/HOL/Multivariate_Analysis/Derivative.thy	Wed Dec 30 11:37:29 2015 +0100
@@ -2471,7 +2471,7 @@
     unfolding has_vector_derivative_def has_derivative_iff_norm
     using assms by (intro conj_cong Lim_cong_within refl) auto
   then show ?thesis
-    using has_vector_derivative_within_subset[OF f `s \<subseteq> t`] by simp
+    using has_vector_derivative_within_subset[OF f \<open>s \<subseteq> t\<close>] by simp
 qed
 
 lemma has_vector_derivative_transform_within: