diff --git a/src/system/kernel/locks/user_mutex.cpp b/src/system/kernel/locks/user_mutex.cpp
index d6fb65b8e7..dad7328d43 100644
--- a/src/system/kernel/locks/user_mutex.cpp
+++ b/src/system/kernel/locks/user_mutex.cpp
@@ -222,9 +222,14 @@ user_mutex_unblock_locked(int32* mutex, phys_addr_t physicalAddress, uint32 flag
 	}
 
 	// Someone is waiting: try to hand off the lock to them, if possible.
-	int32 oldValue = user_atomic_or(mutex, B_USER_MUTEX_LOCKED);
-	if ((oldValue & B_USER_MUTEX_LOCKED) != 0)
-		return;
+	int32 oldValue = 0;
+	if ((flags & B_USER_MUTEX_UNBLOCK_ALL) == 0) {
+		oldValue = user_atomic_or(mutex, B_USER_MUTEX_LOCKED);
+		if ((oldValue & B_USER_MUTEX_LOCKED) != 0)
+			return;
+	} else {
+		oldValue = user_atomic_get(mutex);
+	}
 
 	// unblock the first thread
 	entry->locked = true;
diff --git a/src/system/libroot/posix/pthread/pthread_barrier.cpp b/src/system/libroot/posix/pthread/pthread_barrier.cpp
index 470fa1e6aa..c484165f72 100644
--- a/src/system/libroot/posix/pthread/pthread_barrier.cpp
+++ b/src/system/libroot/posix/pthread/pthread_barrier.cpp
@@ -97,7 +97,6 @@ pthread_barrier_wait(pthread_barrier_t* barrier)
 
 		// Wake everyone else up.
 		barrier->waiter_count = (-barrier->waiter_max) + 1;
-		atomic_and((int32*)&barrier->lock, ~(int32)B_USER_MUTEX_LOCKED);
 		_kern_mutex_unblock((int32*)&barrier->lock, B_USER_MUTEX_UNBLOCK_ALL);
 
 		// Return with the barrier mutex still locked, as waiter_count < 0.