diff --git a/index.js b/index.js
index b0f6abe..841bb7e 100644
--- a/index.js
+++ b/index.js
@@ -103,7 +103,7 @@ module.exports = function serialize(obj, options) {
             return '@__U-' + UID + '-' + (undefs.push(origValue) - 1) + '__@';
         }
 
-        if (origValue === Infinity) {
+        if (type === 'number' && !isNaN(origValue) && !isFinite(origValue)) {
             return '@__I-' + UID + '-' + (infinities.push(origValue) - 1) + '__@';
         }
 
@@ -209,7 +209,7 @@ module.exports = function serialize(obj, options) {
         }
 
         if (type === 'I') {
-            return 'Infinity';
+            return infinities[valueIndex];
         }
 
         var fn = functions[valueIndex];
diff --git a/test/unit/serialize.js b/test/unit/serialize.js
index b160cdc..52e98d4 100644
--- a/test/unit/serialize.js
+++ b/test/unit/serialize.js
@@ -388,6 +388,16 @@ describe('serialize( obj )', function () {
             var d = eval(serialize(Infinity));
             expect(d).to.equal(Infinity);
         });
+
+        it('should serialize -Infinity', function () {
+            expect(serialize(-Infinity)).to.equal('-Infinity');
+            expect(serialize({t: [-Infinity]})).to.be.a('string').equal('{"t":[-Infinity]}');
+        });
+
+        it('should deserialize -Infinity', function () {
+            var d = eval(serialize(-Infinity));
+            expect(d).to.equal(-Infinity);
+        });
     });
 
     describe('XSS', function () {