diff --git a/quantum/impl/quantum_spinlock_impl.h b/quantum/impl/quantum_spinlock_impl.h
index b502ac8..f761f5d 100644
--- a/quantum/impl/quantum_spinlock_impl.h
+++ b/quantum/impl/quantum_spinlock_impl.h
@@ -98,7 +98,7 @@ bool SpinLock::Guard::tryLock()
 inline
 void SpinLock::Guard::lock()
 {
-    assert(!_spinlock.isLocked());
+    assert(!_ownsLock);
     _spinlock.lock();
     _ownsLock = true;
 }