diff --git a/src/lib.rs b/src/lib.rs
index bb2c21d..b9de136 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -69,10 +69,13 @@ pub fn unlink_id(id: i32) -> Result<(), SysvMqError> {
     }
 }
 
-pub fn unlink_key(key: i32) -> Result<(), SysvMqError> {
+pub fn id_from_key(key: i32) -> Result<i32, SysvMqError> {
     let id = unsafe { msgget(key, 0) };
 
-    unlink_id(id)
+    match id {
+        -1 => Err(SysvMqError::ErrnoError(Errno::from_i32(errno()).desc())),
+        id => Ok(id),
+    }
 }
 
 pub struct SysvMq<T> {