diff --git a/keystore/user_state.h b/keystore/user_state.h
index 9403552..b0671e3 100644
--- a/keystore/user_state.h
+++ b/keystore/user_state.h
@@ -78,7 +78,7 @@
     static const int SHA1_DIGEST_SIZE_BYTES = 16;
     static const int SHA256_DIGEST_SIZE_BYTES = 32;
 
-    static const int MASTER_KEY_SIZE_BYTES = SHA1_DIGEST_SIZE_BYTES;
+    static const int MASTER_KEY_SIZE_BYTES = SHA256_DIGEST_SIZE_BYTES;
     static const int MASTER_KEY_SIZE_BITS = MASTER_KEY_SIZE_BYTES * 8;
 
     static const int MAX_RETRY = 4;