diff --git a/lib/server.js b/lib/server.js
index a787a0d..9786c46 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -981,7 +981,7 @@ WalletService.prototype.getBalance = function(opts, cb) {
       if (err) {
         log.error('Could not compute size of send max transaction', err);
       }
-      balance.totalBytesToSendMax = size || 0;
+      balance.totalBytesToSendMax = size || null;
       return cb(null, balance);
     });
   });