diff --git a/rwlockguard.cpp b/rwlockguard.cpp
index c9cb7a4..9e091a3 100644
--- a/rwlockguard.cpp
+++ b/rwlockguard.cpp
@@ -21,7 +21,7 @@ void RWLockGuard::wrlock()
 
 void RWLockGuard::rdlock()
 {
-    if (pthread_rwlock_wrlock(rwlock) != 0)
+    if (pthread_rwlock_rdlock(rwlock) != 0)
         throw std::runtime_error("rdlock failed.");
 }