diff --git a/src/libstd/sys/unix/backtrace.rs b/src/libstd/sys/unix/backtrace.rs
index 3fa9f5d07aa..74ab04978cb 100644
--- a/src/libstd/sys/unix/backtrace.rs
+++ b/src/libstd/sys/unix/backtrace.rs
@@ -118,7 +118,7 @@ pub fn write(w: &mut Write) -> io::Result<()> {
     // local, it still displays much nicer backtraces when a
     // couple of tasks panic simultaneously
     static LOCK: StaticMutex = MUTEX_INIT;
-    let _g = unsafe { LOCK.lock() };
+    let _g = LOCK.lock();
 
     try!(writeln!(w, "stack backtrace:"));
     // 100 lines should be enough