diff --git a/src/id.rs b/src/id.rs
index 5c1e946..449ef51 100644
--- a/src/id.rs
+++ b/src/id.rs
@@ -17,6 +17,10 @@ pub struct Id(pub [u8; RAW_LEN]);
 
 impl Id {
     /// Create an Id from a bytes slice.
+    ///
+    /// # Errors
+    ///
+    /// Will return `Err` if the length of `bytes` is invalid.
     pub fn from_bytes(bytes: &[u8]) -> Result<Self, ParseIdError> {
         if bytes.len() != RAW_LEN {
             return Err(ParseIdError::InvalidLength(bytes.len()));
@@ -65,6 +69,7 @@ impl Id {
     }
 
     /// Returns true if this is a "zero" ID
+    #[must_use]
     pub fn is_zero(&self) -> bool {
         self.0 == ZERO.0
     }
diff --git a/src/machine_id.rs b/src/machine_id.rs
index 7db1ee5..ff5f5e6 100644
--- a/src/machine_id.rs
+++ b/src/machine_id.rs
@@ -1,5 +1,5 @@
 use rand::RngCore;
-#[cfg(any(target_os = "macos"))]
+#[cfg(target_os = "macos")]
 use sysctl::{Sysctl, SysctlError};
 
 // https://github.com/rs/xid/blob/efa678f304ab65d6d57eedcb086798381ae22206/id.go#L117