diff --git a/media/libstagefright/foundation/ABitReader.cpp b/media/libstagefright/foundation/ABitReader.cpp
index beb5cc0..1582b67 100644
--- a/media/libstagefright/foundation/ABitReader.cpp
+++ b/media/libstagefright/foundation/ABitReader.cpp
@@ -114,7 +114,7 @@
         return false;
     }
 
-    ssize_t numBitsRemaining = n - mNumBitsLeft;
+    ssize_t numBitsRemaining = (ssize_t)n - (ssize_t)mNumBitsLeft;
 
     size_t size = mSize;
     const uint8_t *data = mData;