diff --git a/lib/server.js b/lib/server.js
index d30bedd..ad1c871 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -2448,16 +2448,28 @@ WalletService.prototype._normalizeTxHistory = function(txs) {
   });
 };
 
-WalletService._cachedBlockheight = {};
+WalletService._cachedBlockheight;
+
+WalletService._initBlockchainHeightCache = function() {
+  if (WalletService._cachedBlockheight) return;
+  WalletService._cachedBlockheight = {
+    livenet: {},
+    testnet: {}
+  };
+};
+
 WalletService._clearBlockchainHeightCache = function() {
-  WalletService._cachedBlockheight.current = null;
+  WalletService._initBlockchainHeightCache();
+  WalletService._cachedBlockheight.livenet.current = null;
+  WalletService._cachedBlockheight.testnet.current = null;
 };
 
 WalletService.prototype._getBlockchainHeight = function(network, cb) {
   var self = this;
 
   var now = Date.now();
-  var cache = WalletService._cachedBlockheight;
+  WalletService._initBlockchainHeightCache();
+  var cache = WalletService._cachedBlockheight[network];
 
   function fetchFromBlockchain(cb) {
     var bc = self._getBlockchainExplorer(network);
diff --git a/test/integration/server.js b/test/integration/server.js
index 9d61314..b032293 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -5930,7 +5930,7 @@ describe('Wallet service', function() {
     it('should get real # of confirmations based on current block height', function(done) {
       var _confirmations = Defaults.CONFIRMATIONS_TO_START_CACHING;
       Defaults.CONFIRMATIONS_TO_START_CACHING = 6;
-      WalletService._cachedBlockheight = {};
+      WalletService._cachedBlockheight = null;
 
       var h = helpers.historyCacheTest(20);
       _.each(h, function(x, i) {
@@ -5989,7 +5989,7 @@ describe('Wallet service', function() {
     it('should get cached # of confirmations if current height unknown', function(done) {
       var _confirmations = Defaults.CONFIRMATIONS_TO_START_CACHING;
       Defaults.CONFIRMATIONS_TO_START_CACHING = 6;
-      WalletService._cachedBlockheight = {};
+      WalletService._cachedBlockheight = null;
 
       var h = helpers.historyCacheTest(20);
       helpers.stubHistory(h);