diff --git a/tokio/src/fs/file.rs b/tokio/src/fs/file.rs
index 033b2982c7d..fcc78bd1b73 100644
--- a/tokio/src/fs/file.rs
+++ b/tokio/src/fs/file.rs
@@ -233,13 +233,14 @@ impl File {
     /// let std_file = std::fs::File::open("foo.txt").unwrap();
     /// let file = tokio::fs::File::from_std(std_file);
     /// ```
-    pub fn from_std(std: StdFile) -> File {
+    pub fn from_std(mut std: StdFile) -> File {
+        let pos = std.stream_position().unwrap_or(0);
         File {
             std: Arc::new(std),
             inner: Mutex::new(Inner {
                 state: State::Idle(Some(Buf::with_capacity(0))),
                 last_write_err: None,
-                pos: 0,
+                pos,
             }),
         }
     }
diff --git a/tokio/src/fs/mocks.rs b/tokio/src/fs/mocks.rs
index b718ed54f95..8fd4473a4f5 100644
--- a/tokio/src/fs/mocks.rs
+++ b/tokio/src/fs/mocks.rs
@@ -59,6 +59,12 @@ impl Read for MockFile {
     }
 }
 
+impl Seek for MockFile {
+    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
+        self.inner_seek(pos)
+    }
+}
+
 impl Read for &'_ MockFile {
     fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
         self.inner_read(dst)