diff --git a/src/pcm.rs b/src/pcm.rs
index c39cbce..f340509 100644
--- a/src/pcm.rs
+++ b/src/pcm.rs
@@ -234,6 +234,13 @@ impl PCM {
         self.verify_format(S::FORMAT).map(|_| IO::new(self))
     }
 
+    /// Creates IO without checking [`S`] is valid type.
+    ///
+    /// SAFETY: Caller must guarantee [`S`] is valid type for this PCM stream
+    pub unsafe fn io_unchecked<S: IoFormat>(&self) -> IO<S> {
+        IO::new_unchecked(self)
+    }
+
     #[deprecated(note = "renamed to io_bytes")]
     pub fn io(&self) -> IO<u8> { IO::new(self) }
     pub fn io_bytes(&self) -> IO<u8> { IO::new(self) }
@@ -359,6 +366,11 @@ impl<'a, S: Copy> IO<'a, S> {
         IO(a, PhantomData)
     }
 
+    unsafe fn new_unchecked(a: &'a PCM) -> IO<'a, S> {
+        a.1.set(true);
+        IO(a, PhantomData)
+    }
+
     fn to_frames(&self, b: usize) -> alsa::snd_pcm_uframes_t {
         // TODO: Do we need to check for overflow here?
         self.0.bytes_to_frames((b * size_of::<S>()) as isize) as alsa::snd_pcm_uframes_t