diff --git a/libs/binder/include/binder/ProcessState.h b/libs/binder/include/binder/ProcessState.h
index 8dee3ad..8a1f7e2 100644
--- a/libs/binder/include/binder/ProcessState.h
+++ b/libs/binder/include/binder/ProcessState.h
@@ -138,7 +138,7 @@
             String8             mRootDir;
             bool                mThreadPoolStarted;
     volatile int32_t            mThreadPoolSeq;
-            size_t              mMmapSize;
+            const size_t        mMmapSize;
 
             CallRestriction     mCallRestriction;
 };