diff --git a/underscore/underscore-tests.ts b/underscore/underscore-tests.ts
index 3fb993a3d..60c1708d0 100644
--- a/underscore/underscore-tests.ts
+++ b/underscore/underscore-tests.ts
@@ -11,6 +11,7 @@ _.map({ one: 1, two: 2, three: 3 }, (value, key) => value * 3);
 //var sum = _.reduce([1, 2, 3], (memo, num) => memo + num, 0);	// https://typescript.codeplex.com/workitem/1960
 var sum = _.reduce<number, number>([1, 2, 3], (memo, num) => memo + num, 0);
 sum = _.reduce<number, number>([1, 2, 3], (memo, num) => memo + num); // memo is optional #issue 5 github
+sum = _.reduce<string, number>({'a':'1', 'b':'2', 'c':'3'}, (memo, numstr) => memo + (+numstr));
 
 var list = [[0, 1], [2, 3], [4, 5]];
 //var flat = _.reduceRight(list, (a, b) => a.concat(b), []);	// https://typescript.codeplex.com/workitem/1960
diff --git a/underscore/underscore.d.ts b/underscore/underscore.d.ts
index 7ff9aa5eb..03088bffd 100644
--- a/underscore/underscore.d.ts
+++ b/underscore/underscore.d.ts
@@ -41,18 +41,6 @@ declare module _ {
 		escape?: RegExp;
 	}
 
-	interface ListIterator<T, TResult> {
-		(value: T, index: number, list: T[]): TResult;
-	}
-
-	interface ObjectIterator<T, TResult> {
-		(element: T, key: string, list: any): TResult;
-	}
-
-	interface MemoIterator<T, TResult> {
-		(prev: TResult, curr: T, index: number, list: T[]): TResult;
-	}
-
 	interface Collection<T> { }
 
 	// Common interface between Arrays and jQuery objects
@@ -64,6 +52,22 @@ declare module _ {
 	interface Dictionary<T> extends Collection<T> {
 		[index: string]: T;
 	}
+
+	interface ListIterator<T, TResult> {
+		(value: T, index: number, list: List<T>): TResult;
+	}
+
+	interface ObjectIterator<T, TResult> {
+		(element: T, key: string, list: Dictionary<T>): TResult;
+	}
+
+	interface MemoIterator<T, TResult> {
+		(prev: TResult, curr: T, index: number, list: List<T>): TResult;
+	}
+
+	interface MemoObjectIterator<T, TResult> {
+		(prev: TResult, curr: T, key: string, list: Dictionary<T>): TResult;
+	}
 }
 
 interface UnderscoreStatic {
@@ -181,7 +185,7 @@ interface UnderscoreStatic {
 
 	reduce<T, TResult>(
 		list: _.Dictionary<T>,
-		iterator: _.ObjectIterator<T, TResult>,
+		iterator: _.MemoObjectIterator<T, TResult>,
 		memo?: TResult,
 		context?: any): TResult;