diff --git a/src/libcoretest/char.rs b/src/libcoretest/char.rs
index bed38f8c29666..734e579ec696b 100644
--- a/src/libcoretest/char.rs
+++ b/src/libcoretest/char.rs
@@ -33,12 +33,12 @@ fn test_is_uppercase() {
 #[test]
 fn test_is_whitespace() {
     assert!(' '.is_whitespace());
-    assert!('\u2007'.is_whitespace());
+    assert!('\u{2007}'.is_whitespace());
     assert!('\t'.is_whitespace());
     assert!('\n'.is_whitespace());
     assert!(!'a'.is_whitespace());
     assert!(!'_'.is_whitespace());
-    assert!(!'\u0000'.is_whitespace());
+    assert!(!'\u{0000}'.is_whitespace());
 }
 
 #[test]
@@ -92,15 +92,15 @@ fn test_to_uppercase() {
 
 #[test]
 fn test_is_control() {
-    assert!('\u0000'.is_control());
-    assert!('\u0003'.is_control());
-    assert!('\u0006'.is_control());
-    assert!('\u0009'.is_control());
-    assert!('\u007f'.is_control());
-    assert!('\u0092'.is_control());
-    assert!(!'\u0020'.is_control());
-    assert!(!'\u0055'.is_control());
-    assert!(!'\u0068'.is_control());
+    assert!('\u{0000}'.is_control());
+    assert!('\u{0003}'.is_control());
+    assert!('\u{0006}'.is_control());
+    assert!('\u{0009}'.is_control());
+    assert!('\u{007f}'.is_control());
+    assert!('\u{0092}'.is_control());
+    assert!(!'\u{0020}'.is_control());
+    assert!(!'\u{0055}'.is_control());
+    assert!(!'\u{0068}'.is_control());
 }
 
 #[test]
@@ -175,9 +175,9 @@ fn test_encode_utf8() {
     }
 
     check('x', &[0x78]);
-    check('\u00e9', &[0xc3, 0xa9]);
-    check('\ua66e', &[0xea, 0x99, 0xae]);
-    check('\U0001f4a9', &[0xf0, 0x9f, 0x92, 0xa9]);
+    check('\u{00e9}', &[0xc3, 0xa9]);
+    check('\u{a66e}', &[0xea, 0x99, 0xae]);
+    check('\u{01f4a9}', &[0xf0, 0x9f, 0x92, 0xa9]);
 }
 
 #[test]
@@ -189,17 +189,17 @@ fn test_encode_utf16() {
     }
 
     check('x', &[0x0078]);
-    check('\u00e9', &[0x00e9]);
-    check('\ua66e', &[0xa66e]);
-    check('\U0001f4a9', &[0xd83d, 0xdca9]);
+    check('\u{00e9}', &[0x00e9]);
+    check('\u{a66e}', &[0xa66e]);
+    check('\u{01f4a9}', &[0xd83d, 0xdca9]);
 }
 
 #[test]
 fn test_len_utf16() {
     assert!('x'.len_utf16() == 1);
-    assert!('\u00e9'.len_utf16() == 1);
-    assert!('\ua66e'.len_utf16() == 1);
-    assert!('\U0001f4a9'.len_utf16() == 2);
+    assert!('\u{00e9}'.len_utf16() == 1);
+    assert!('\u{a66e}'.len_utf16() == 1);
+    assert!('\u{01f4a9}'.len_utf16() == 2);
 }
 
 #[test]
@@ -216,15 +216,15 @@ fn test_width() {
     assert_eq!('ｈ'.width(false),Some(2));
     assert_eq!('ｈ'.width(true),Some(2));
 
-    assert_eq!('\u00AD'.width(false),Some(1));
-    assert_eq!('\u00AD'.width(true),Some(1));
+    assert_eq!('\u{00AD}'.width(false),Some(1));
+    assert_eq!('\u{00AD}'.width(true),Some(1));
 
-    assert_eq!('\u1160'.width(false),Some(0));
-    assert_eq!('\u1160'.width(true),Some(0));
+    assert_eq!('\u{1160}'.width(false),Some(0));
+    assert_eq!('\u{1160}'.width(true),Some(0));
 
-    assert_eq!('\u00a1'.width(false),Some(1));
-    assert_eq!('\u00a1'.width(true),Some(2));
+    assert_eq!('\u{00a1}'.width(false),Some(1));
+    assert_eq!('\u{00a1}'.width(true),Some(2));
 
-    assert_eq!('\u0300'.width(false),Some(0));
-    assert_eq!('\u0300'.width(true),Some(0));
+    assert_eq!('\u{0300}'.width(false),Some(0));
+    assert_eq!('\u{0300}'.width(true),Some(0));
 }
diff --git a/src/libcoretest/str.rs b/src/libcoretest/str.rs
index 763fcccdbfdc8..bfabf9660b9be 100644
--- a/src/libcoretest/str.rs
+++ b/src/libcoretest/str.rs
@@ -118,6 +118,6 @@ fn test_rev_split_char_iterator_no_trailing() {
 #[test]
 fn test_utf16_code_units() {
     use core::str::Utf16Encoder;
-    assert_eq!(Utf16Encoder::new(vec!['é', '\U0001F4A9'].into_iter()).collect::<Vec<u16>>(),
+    assert_eq!(Utf16Encoder::new(vec!['é', '\u{01F4A9}'].into_iter()).collect::<Vec<u16>>(),
                vec![0xE9, 0xD83D, 0xDCA9])
 }
diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index 6d143329b0c30..34f0cefb81a96 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -2760,9 +2760,9 @@ mod tests {
     fn test_write_char() {
         check_encoder_for_simple!('a', "\"a\"");
         check_encoder_for_simple!('\t', "\"\\t\"");
-        check_encoder_for_simple!('\u00a0', "\"\u00a0\"");
-        check_encoder_for_simple!('\uabcd', "\"\uabcd\"");
-        check_encoder_for_simple!('\U0010ffff', "\"\U0010ffff\"");
+        check_encoder_for_simple!('\u{a0}', "\"\u{a0}\"");
+        check_encoder_for_simple!('\u{abcd}', "\"\u{abcd}\"");
+        check_encoder_for_simple!('\u{10ffff}', "\"\u{10ffff}\"");
     }
 
     #[test]