diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index ecd27fa99676..1e8f699b520f 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -1149,7 +1149,9 @@ fn suggest_change_mut(
                     new_trait_ref.to_predicate(),
                 );
 
-                if self.predicate_may_hold(&new_obligation) {
+                if self.evaluate_obligation_no_overflow(
+                    &new_obligation,
+                ).must_apply_modulo_regions() {
                     let sp = self.tcx.sess.source_map()
                         .span_take_while(span, |c| c.is_whitespace() || *c == '&');
                     if points_at_arg &&
diff --git a/src/librustc/traits/query/evaluate_obligation.rs b/src/librustc/traits/query/evaluate_obligation.rs
index 17684df7e9b8..0d426cab9b75 100644
--- a/src/librustc/traits/query/evaluate_obligation.rs
+++ b/src/librustc/traits/query/evaluate_obligation.rs
@@ -56,7 +56,7 @@ pub fn evaluate_obligation(
     // Helper function that canonicalizes and runs the query. If an
     // overflow results, we re-run it in the local context so we can
     // report a nice error.
-    fn evaluate_obligation_no_overflow(
+    crate fn evaluate_obligation_no_overflow(
         &self,
         obligation: &PredicateObligation<'tcx>,
     ) -> EvaluationResult {
diff --git a/src/test/ui/parser/lex-bad-char-literals-6.stderr b/src/test/ui/parser/lex-bad-char-literals-6.stderr
index dc6e1e6e972c..a7bbe05e94b7 100644
--- a/src/test/ui/parser/lex-bad-char-literals-6.stderr
+++ b/src/test/ui/parser/lex-bad-char-literals-6.stderr
@@ -35,7 +35,6 @@ LL |     if x == y {}
    |          ^^ no implementation for `&str == char`
    |
    = help: the trait `std::cmp::PartialEq<char>` is not implemented for `&str`
-   = note: `std::cmp::PartialEq<char>` is implemented for `&mut str`, but not for `&str`
 
 error[E0308]: mismatched types
   --> $DIR/lex-bad-char-literals-6.rs:15:20
@@ -53,7 +52,6 @@ LL |     if x == z {}
    |          ^^ no implementation for `&str == char`
    |
    = help: the trait `std::cmp::PartialEq<char>` is not implemented for `&str`
-   = note: `std::cmp::PartialEq<char>` is implemented for `&mut str`, but not for `&str`
 
 error: aborting due to 6 previous errors