diff --git a/futures-util/src/io/mod.rs b/futures-util/src/io/mod.rs
index 4f474f757..ff430d76b 100644
--- a/futures-util/src/io/mod.rs
+++ b/futures-util/src/io/mod.rs
@@ -807,11 +807,11 @@ pub trait AsyncBufReadExt: AsyncBufRead {
     /// use futures::io::{AsyncBufReadExt, Cursor};
     /// use futures::stream::StreamExt;
     ///
-    /// let cursor = Cursor::new(b"lorem\nipsum\r\ndolor");
+    /// let cursor = Cursor::new(b"lorem\nipsum\xc2\r\ndolor");
     ///
-    /// let mut lines_stream = cursor.lines().map(|l| l.unwrap());
+    /// let mut lines_stream = cursor.lines().map(|l| l.unwrap_or(String::from("invalid UTF_8")));
     /// assert_eq!(lines_stream.next().await, Some(String::from("lorem")));
-    /// assert_eq!(lines_stream.next().await, Some(String::from("ipsum")));
+    /// assert_eq!(lines_stream.next().await, Some(String::from("invalid UTF_8")));
     /// assert_eq!(lines_stream.next().await, Some(String::from("dolor")));
     /// assert_eq!(lines_stream.next().await, None);
     /// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap();
diff --git a/futures-util/src/io/read_line.rs b/futures-util/src/io/read_line.rs
index e1b8fc945..df782c957 100644
--- a/futures-util/src/io/read_line.rs
+++ b/futures-util/src/io/read_line.rs
@@ -35,6 +35,7 @@ pub(super) fn read_line_internal<R: AsyncBufRead + ?Sized>(
 ) -> Poll<io::Result<usize>> {
     let ret = ready!(read_until_internal(reader, cx, b'\n', bytes, read));
     if str::from_utf8(bytes).is_err() {
+        bytes.clear();
         Poll::Ready(ret.and_then(|_| {
             Err(io::Error::new(io::ErrorKind::InvalidData, "stream did not contain valid UTF-8"))
         }))