diff --git a/third_party/libuweave/src/macaroon_caveat.c b/third_party/libuweave/src/macaroon_caveat.c
index a04c30d..594f9de 100644
--- a/third_party/libuweave/src/macaroon_caveat.c
+++ b/third_party/libuweave/src/macaroon_caveat.c
@@ -12,7 +12,7 @@
 
 // TODO(bozhu): Find a better way to pre-allocate memory for HMACc computations?
 // Are C99 variable-length arrays allowed on embedded devices?
-#define HMAC_STATE_BUFFER_SIZE 300
+#define HMAC_STATE_BUFFER_SIZE 1024
 
 static bool create_caveat_(UwMacaroonCaveatType type, const void* value,
                            size_t value_len, uint8_t* buffer,
diff --git a/third_party/libuweave/src/macaroon_caveat.h b/third_party/libuweave/src/macaroon_caveat.h
index 5f2c384..78373c8 100644
--- a/third_party/libuweave/src/macaroon_caveat.h
+++ b/third_party/libuweave/src/macaroon_caveat.h
@@ -24,6 +24,13 @@
   kUwMacaroonCaveatTypeSessionIdentifier = 16
 } UwMacaroonCaveatType;
 
+typedef enum {
+  kUwMacaroonCaveatScopeTypeOwner = 0,
+  kUwMacaroonCaveatScopeTypeManager = 1,
+  kUwMacaroonCaveatScopeTypeUser = 2,
+  kUwMacaroonCaveatScopeTypeViewer = 3,
+} UwMacaroonCaveatScopeType;
+
 bool uw_macaroon_caveat_create_without_value_(UwMacaroonCaveatType type,
                                               uint8_t* buffer,
                                               size_t buffer_size,