diff --git a/tokio/src/io/util/async_read_ext.rs b/tokio/src/io/util/async_read_ext.rs
index ebcbce646f1..e715f9de3d1 100644
--- a/tokio/src/io/util/async_read_ext.rs
+++ b/tokio/src/io/util/async_read_ext.rs
@@ -35,7 +35,7 @@ cfg_io_util! {
 
     /// Reads bytes from a source.
     ///
-    /// Implemented as an extention trait, adding utility methods to all
+    /// Implemented as an extension trait, adding utility methods to all
     /// [`AsyncRead`] types. Callers will tend to import this trait instead of
     /// [`AsyncRead`].
     ///
diff --git a/tokio/src/io/util/async_write_ext.rs b/tokio/src/io/util/async_write_ext.rs
index dc500f2f281..978062eb2b0 100644
--- a/tokio/src/io/util/async_write_ext.rs
+++ b/tokio/src/io/util/async_write_ext.rs
@@ -35,7 +35,7 @@ cfg_io_util! {
 
     /// Writes bytes to a sink.
     ///
-    /// Implemented as an extention trait, adding utility methods to all
+    /// Implemented as an extension trait, adding utility methods to all
     /// [`AsyncWrite`] types. Callers will tend to import this trait instead of
     /// [`AsyncWrite`].
     ///