diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 5450f2d7c31a3..69625c3845a95 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -858,7 +858,7 @@ mod tests {
     fn from_utf8_lossy_100_multibyte(b: &mut Bencher) {
         let s = "𐌀𐌖𐌋𐌄𐌑𐌉ปรدولة\
             الكويتทศไทย中华𐍅𐌿𐌻𐍆𐌹𐌻𐌰".as_bytes();
-        assert_eq!(100, s.len());
+        assert_eq!(212, s.len());
         b.iter(|| {
             let _ = String::from_utf8_lossy(s);
         });