diff --git a/Stellar-ledger.x b/Stellar-ledger.x
index 77b3d30..7210331 100644
--- a/Stellar-ledger.x
+++ b/Stellar-ledger.x
@@ -61,13 +61,13 @@ struct StellarValue
     case STELLAR_VALUE_SIGNED_MS:
         struct
         {
-            uint32 closeTimeMs; // millisecond component of closeTime, [0, 999]
+            TimePointMilliseconds closeTimeMs; // closeTime == closeTimeMs / 1000
             LedgerCloseValueSignature lcValueSignature;
         } signedMsValue;
     case STELLAR_VALUE_EMPTY_TX_SET_MS:
         struct
         {
-            uint32 closeTimeMs; // millisecond component of closeTime, [0, 999]
+            TimePointMilliseconds closeTimeMs; // closeTime == closeTimeMs / 1000
             Hash txSetHash;
             Hash previousLedgerHash;
             uint32 previousLedgerVersion;
diff --git a/Stellar-types.x b/Stellar-types.x
index ac18496..79b127e 100644
--- a/Stellar-types.x
+++ b/Stellar-types.x
@@ -16,6 +16,10 @@ typedef hyper int64;
 
 typedef uint64 TimePoint;
 typedef uint64 Duration;
+#ifdef MS_CLOSE_TIME
+// Milliseconds since the Unix epoch. TimePoint is whole seconds.
+typedef uint64 TimePointMilliseconds;
+#endif // MS_CLOSE_TIME
 
 // An ExtensionPoint is always marshaled as a 32-bit 0 value.  At a
 // later point, it can be replaced by a different union so as to