diff --git a/types/d3-selection/d3-selection-tests.ts b/types/d3-selection/d3-selection-tests.ts
index 318243dcfc..354cdbd96f 100644
--- a/types/d3-selection/d3-selection-tests.ts
+++ b/types/d3-selection/d3-selection-tests.ts
@@ -771,6 +771,21 @@ tr = d3Selection.select('body')
     .data<number[]>([{test: 1}, {test: 2}]) // fails, using this data statement instead, would fail because of its type parameter not being met by input
     .enter().append('tr');
 
+let li: d3Selection.Selection<HTMLLIElement, number, HTMLElement, any>;
+li = d3Selection.select('li')
+    .data(matrix[0], d => <number> d)
+    .enter().append('li');
+
+const tr1 = d3Selection.select("body")
+    .append("table")
+    .selectAll("tr")
+    .data(matrix)
+    .join("tr")
+    .selectAll("td")
+    .data(d => d, e => <number> e)
+    .join("td")
+    .text(d => d);
+
 nMatrix = tr.data(); // i.e. matrix
 
 let td: d3Selection.Selection<HTMLTableDataCellElement, number, HTMLTableRowElement, number[]>;
diff --git a/types/d3-selection/index.d.ts b/types/d3-selection/index.d.ts
index 6f9e2f93be..4d23693039 100644
--- a/types/d3-selection/index.d.ts
+++ b/types/d3-selection/index.d.ts
@@ -20,6 +20,11 @@
  */
 export type BaseType = Element | EnterElement | Document | Window | null;
 
+/**
+ * KeyType serves as alias for valid types that d3 supports as key for data binding
+ */
+export type KeyType = string | number;
+
 /**
  * A helper interface which covers arguments like NodeListOf<T> or HTMLCollectionOf<T>
  * argument types
@@ -747,7 +752,7 @@ export interface Selection<GElement extends BaseType, Datum, PElement extends Ba
      * The datum for a given key is assigned to the element with the matching key. If multiple elements have the same key,
      * the duplicate elements are put into the exit selection; if multiple data have the same key, the duplicate data are put into the enter selection.
      */
-    data<NewDatum>(data: NewDatum[], key?: ValueFn<GElement | PElement, Datum | NewDatum, string>): Selection<GElement, NewDatum, PElement, PDatum>;
+    data<NewDatum>(data: NewDatum[], key?: ValueFn<GElement | PElement, Datum | NewDatum, KeyType>): Selection<GElement, NewDatum, PElement, PDatum>;
     /**
      * Joins the data returned by the specified value function with the selected elements, returning a new selection that it represents
      * the update selection: the elements successfully bound to data. Also defines the enter and exit selections on
@@ -780,7 +785,7 @@ export interface Selection<GElement extends BaseType, Datum, PElement extends Ba
      * The datum for a given key is assigned to the element with the matching key. If multiple elements have the same key,
      * the duplicate elements are put into the exit selection; if multiple data have the same key, the duplicate data are put into the enter selection.
      */
-    data<NewDatum>(data: ValueFn<PElement, PDatum, NewDatum[]>, key?: ValueFn<GElement | PElement, Datum | NewDatum, string>): Selection<GElement, NewDatum, PElement, PDatum>;
+    data<NewDatum>(data: ValueFn<PElement, PDatum, NewDatum[]>, key?: ValueFn<GElement | PElement, Datum | NewDatum, KeyType>): Selection<GElement, NewDatum, PElement, PDatum>;
 
     /**
      * Appends, removes and reorders elements as necessary to match the data that was previously bound by `selection.data`, returning the merged enter and update selection.