diff --git a/libs/binder/Binder.cpp b/libs/binder/Binder.cpp
index d964d25..d5bdd1c 100644
--- a/libs/binder/Binder.cpp
+++ b/libs/binder/Binder.cpp
@@ -29,6 +29,16 @@
 
 namespace android {
 
+// Service implementations inherit from BBinder and IBinder, and this is frozen
+// in prebuilts.
+#ifdef __LP64__
+static_assert(sizeof(IBinder) == 24);
+static_assert(sizeof(BBinder) == 40);
+#else
+static_assert(sizeof(IBinder) == 12);
+static_assert(sizeof(BBinder) == 20);
+#endif
+
 // ---------------------------------------------------------------------------
 
 IBinder::IBinder()
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 98ca829..39d6a2e 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -78,7 +78,11 @@
 namespace android {
 
 // many things compile this into prebuilts on the stack
-static_assert(sizeof(Parcel) == 60 || sizeof(Parcel) == 120);
+#ifdef __LP64__
+static_assert(sizeof(Parcel) == 120);
+#else
+static_assert(sizeof(Parcel) == 60);
+#endif
 
 static std::atomic<size_t> gParcelGlobalAllocCount;
 static std::atomic<size_t> gParcelGlobalAllocSize;