diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 2ad45e80dd1..8ac46bf51f1 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -1171,7 +1171,7 @@ pub enum SeekFrom {
     /// Set the offset to the size of this object plus the specified number of
     /// bytes.
     ///
-    /// It is possible to seek beyond the end of an object, but is an error to
+    /// It is possible to seek beyond the end of an object, but it's an error to
     /// seek before byte 0.
     #[stable(feature = "rust1", since = "1.0.0")]
     End(i64),
@@ -1179,7 +1179,7 @@ pub enum SeekFrom {
     /// Set the offset to the current position plus the specified number of
     /// bytes.
     ///
-    /// It is possible to seek beyond the end of an object, but is an error to
+    /// It is possible to seek beyond the end of an object, but it's an error to
     /// seek before byte 0.
     #[stable(feature = "rust1", since = "1.0.0")]
     Current(i64),