diff --git a/src/librustc/ty/print/pretty.rs b/src/librustc/ty/print/pretty.rs
index 10038603f301..95b1519023fa 100644
--- a/src/librustc/ty/print/pretty.rs
+++ b/src/librustc/ty/print/pretty.rs
@@ -1578,7 +1578,7 @@ define_print_and_forward_display! {
                     p!(write("b\""));
                     for &c in slice {
                         for e in std::ascii::escape_default(c) {
-                            p!(write("{}", e));
+                            p!(write("{}", e as char));
                         }
                     }
                     p!(write("\""));
@@ -1594,7 +1594,7 @@ define_print_and_forward_display! {
                     p!(write("b\""));
                     for &c in slice {
                         for e in std::ascii::escape_default(c) {
-                            p!(write("{}", e));
+                            p!(write("{}", e as char));
                         }
                     }
                     p!(write("\""));
diff --git a/src/test/mir-opt/byte_slice.rs b/src/test/mir-opt/byte_slice.rs
index 23faf7e16a7e..7edfa3e1124d 100644
--- a/src/test/mir-opt/byte_slice.rs
+++ b/src/test/mir-opt/byte_slice.rs
@@ -8,7 +8,7 @@ fn main() {
 // END RUST SOURCE
 // START rustc.main.EraseRegions.after.mir
 // ...
-// _1 = const b"102111111";
+// _1 = const b"foo";
 // ...
 // _2 = [const 5u8, const 120u8];
 // ...