diff --git a/os2/2021/11/k1.md b/os2/2021/11/k1.md
index bb5d147..e7df1ad 100644
--- a/os2/2021/11/k1.md
+++ b/os2/2021/11/k1.md
@@ -60,7 +60,7 @@ private:
 };
 class BoundedBuffer {
 public:
-    BoundedBuffer() : numberInBuffer(0) {}
+    BoundedBuffer() : numberInBuffer(0), slotAvailable(&mutex), itemAvailable(&mutex) {}
     void put(Data* d);
     Data* get();
 private: