diff --git a/include/private/surfaceflinger/SharedBufferStack.h b/include/private/surfaceflinger/SharedBufferStack.h
index c3ac317..de54870 100644
--- a/include/private/surfaceflinger/SharedBufferStack.h
+++ b/include/private/surfaceflinger/SharedBufferStack.h
@@ -303,6 +303,7 @@
             : mCapacity(c), mList(0) { }
         status_t add(int value);
         status_t remove(int value);
+        uint32_t getMask() const { return mList; }
 
         class const_iterator {
             friend class BufferList;
diff --git a/libs/surfaceflinger_client/SharedBufferStack.cpp b/libs/surfaceflinger_client/SharedBufferStack.cpp
index e2e1591..8681b59 100644
--- a/libs/surfaceflinger_client/SharedBufferStack.cpp
+++ b/libs/surfaceflinger_client/SharedBufferStack.cpp
@@ -440,7 +440,7 @@
 bool SharedBufferClient::needNewBuffer(int buf) const
 {
     SharedBufferStack& stack( *mSharedStack );
-    const uint32_t mask = 1<<buf;
+    const uint32_t mask = 1<<(31-buf);
     return (android_atomic_and(~mask, &stack.reallocMask) & mask) != 0;
 }
 
@@ -532,7 +532,7 @@
     RWLock::AutoRLock _l(mLock);
 
     SharedBufferStack& stack( *mSharedStack );
-    uint32_t mask = (1<<mNumBuffers)-1;
+    uint32_t mask = mBufferList.getMask();
     android_atomic_or(mask, &stack.reallocMask); 
     return NO_ERROR;
 }