diff --git a/lib/linq.ts b/lib/linq.ts
index 13db3d8..d03a911 100644
--- a/lib/linq.ts
+++ b/lib/linq.ts
@@ -190,7 +190,9 @@ class EnumerableImpl<T> implements Enumerable<T>, Iterable<T>, IEnumerable<T> {
         }
         let result: A = zero;
         for (let value of this) {
-            if (!result) result = Constant.getDefaultVal(typeof (value));
+            if ([null, undefined].indexOf(result) > -1 || (isNaN(result as any) && !result)) 
+                result = Constant.getDefaultVal(typeof (value));
+                
             result = method(result, value);
         }
         return selector(result);
diff --git a/test/immediate.ts b/test/immediate.ts
index 42b23da..6269c72 100644
--- a/test/immediate.ts
+++ b/test/immediate.ts
@@ -33,7 +33,10 @@ describe('Immediate Execution -', function () {
     it('Aggregate() - Transform', function () {
         assert.equal(1814400, Linq.From(simpleArray).Aggregate(1, (a, b) => a * b, o => o / 2));
     });
-
+    
+    it('Aggregate() - Default Value [String]', function () {
+        assert.equal("123", Linq.From([1, 2, 3]).Aggregate("", (c, n) => c.toString() + n.toString()));
+    });
 
 
     // All