diff --git a/test/time/hour-test.js b/test/time/hour-test.js
index 5ea033aa79507..17474aba6ccaa 100644
--- a/test/time/hour-test.js
+++ b/test/time/hour-test.js
@@ -42,14 +42,14 @@ suite.addBatch({
         assert.deepEqual(floor(utc(2011, 10, 06, 09, 01)), utc(2011, 10, 06, 09));
       },
       "NPT": {
-        "observes 15-minute offset": time.zone("Asia/Kathmandu", function(floor) {
+        "observes 15-minute offset": time.zone(345, function(floor) {
           assert.deepEqual(floor(local(2010, 11, 31, 23, 59, 59)), utc(2010, 11, 31, 17, 15));
           assert.deepEqual(floor(local(2011, 00, 01, 00, 00, 00)), utc(2010, 11, 31, 18, 15));
           assert.deepEqual(floor(local(2011, 00, 01, 00, 00, 01)), utc(2010, 11, 31, 18, 15));
         })
       },
       "IST": {
-        "observes 30-minute offset": time.zone("Asia/Calcutta", function(floor) {
+        "observes 30-minute offset": time.zone(330, function(floor) {
           assert.deepEqual(floor(local(2010, 11, 31, 23, 59, 59)), utc(2010, 11, 31, 17, 30));
           assert.deepEqual(floor(local(2011, 00, 01, 00, 00, 00)), utc(2010, 11, 31, 18, 30));
           assert.deepEqual(floor(local(2011, 00, 01, 00, 00, 01)), utc(2010, 11, 31, 18, 30));
@@ -82,14 +82,14 @@ suite.addBatch({
         assert.deepEqual(ceil(utc(2011, 10, 06, 09, 01)), utc(2011, 10, 06, 10));
       },
       "NPT": {
-        "observes 15-minute offset": time.zone("Asia/Kathmandu", function(ceil) {
+        "observes 15-minute offset": time.zone(345, function(ceil) {
           assert.deepEqual(ceil(local(2010, 11, 31, 23, 59, 59)), utc(2010, 11, 31, 18, 15));
           assert.deepEqual(ceil(local(2011, 00, 01, 00, 00, 00)), utc(2010, 11, 31, 18, 15));
           assert.deepEqual(ceil(local(2011, 00, 01, 00, 00, 01)), utc(2010, 11, 31, 19, 15));
         })
       },
       "IST": {
-        "observes 30-minute offset": time.zone("Asia/Calcutta", function(ceil) {
+        "observes 30-minute offset": time.zone(330, function(ceil) {
           assert.deepEqual(ceil(local(2010, 11, 31, 23, 59, 59)), utc(2010, 11, 31, 18, 30));
           assert.deepEqual(ceil(local(2011, 00, 01, 00, 00, 00)), utc(2010, 11, 31, 18, 30));
           assert.deepEqual(ceil(local(2011, 00, 01, 00, 00, 01)), utc(2010, 11, 31, 19, 30));
diff --git a/test/time/hours-test.js b/test/time/hours-test.js
index 24c32e2e6a6d3..f30105e64682e 100644
--- a/test/time/hours-test.js
+++ b/test/time/hours-test.js
@@ -49,7 +49,7 @@ suite.addBatch({
       ]);
     },
     "NPT": {
-      "observes 15-minute offset": tz("Asia/Kathmandu", function(range) {
+      "observes 15-minute offset": time.zone(345, function(range) {
         assert.deepEqual(range(local(2011, 10, 7, 0), local(2011, 10, 7, 3)), [
           utc(2011, 10, 6, 18, 15),
           utc(2011, 10, 6, 19, 15),
@@ -58,7 +58,7 @@ suite.addBatch({
       })
     },
     "IST": {
-      "observes 30-minute offset": tz("Asia/Calcutta", function(range) {
+      "observes 30-minute offset": time.zone(330, function(range) {
         assert.deepEqual(range(local(2011, 10, 7, 0), local(2011, 10, 7, 3)), [
           utc(2011, 10, 6, 18, 30),
           utc(2011, 10, 6, 19, 30),
@@ -109,20 +109,4 @@ suite.addBatch({
   }
 });
 
-function tz(tz, scope) {
-  return function() {
-    var o = process.env.TZ;
-    try {
-      process.env.TZ = tz;
-      new Date(0).toString(); // invalidate node's dst cache
-      new Date().toString();
-      scope.apply(this, arguments);
-    } finally {
-      process.env.TZ = o;
-      new Date(0).toString(); // invalidate node's dst cache
-      new Date().toString();
-    }
-  };
-}
-
 suite.export(module);
diff --git a/test/time/time.js b/test/time/time.js
index 2cf0cd7658945..647e65545c6ac 100644
--- a/test/time/time.js
+++ b/test/time/time.js
@@ -1,7 +1,9 @@
+var offset = 0;
+
 exports.local = function(year, month, day, hours, minutes, seconds, milliseconds) {
   var date = new Date();
   date.setFullYear(year, month, day);
-  date.setHours(hours || 0, minutes || 0, seconds || 0, milliseconds || 0);
+  date.setHours(hours || 0, offset + (minutes || 0), seconds || 0, milliseconds || 0);
   return date;
 };
 
@@ -12,18 +14,19 @@ exports.utc = function(year, month, day, hours, minutes, seconds, milliseconds)
   return date;
 };
 
-exports.zone = function(tz, scope) {
+exports.zone = function(tzOffset, scope) {
   return function() {
-    var o = process.env.TZ;
+    var o = Date.prototype.getTimezoneOffset;
     try {
-      process.env.TZ = tz;
-      new Date(0).toString(); // invalidate node's dst cache
-      new Date().toString();
+      // Note: assumes the dates are not in DST.
+      offset = -tzOffset - new Date(0).getTimezoneOffset();
+      Date.prototype.getTimezoneOffset = function() {
+        return offset;
+      };
       scope.apply(this, arguments);
     } finally {
-      process.env.TZ = o;
-      new Date(0).toString(); // invalidate node's dst cache
-      new Date().toString();
+      offset = 0;
+      Date.prototype.getTimezoneOffset = o;
     }
   };
 };