diff --git a/types/slickgrid/test/index.ts b/types/slickgrid/test/index.ts
index 275d603f4a..0c52658abe 100644
--- a/types/slickgrid/test/index.ts
+++ b/types/slickgrid/test/index.ts
@@ -1,3 +1,5 @@
+declare const htmlElement: HTMLElement;
+
 interface MyData extends Slick.SlickData {
 	title: string;
 	duration: string;
@@ -62,7 +64,7 @@ $('.newSelection');
 grid.setSelectedRows([0, 1, 2]);
 
 class SingleCellSelectionModel extends Slick.SelectionModel<MyData, Slick.Range[]> {
-	private readonly self: SingleCellSelectionModel = null;
+	private readonly self: SingleCellSelectionModel;
 	private _grid: Slick.Grid<MyData>;
 
 	constructor() {
@@ -121,14 +123,14 @@ grid.canCellBeSelected(5, 10);
 
 grid.editActiveCell(new Slick.Editors.Date<MyData>({
 	column: cols[0],
-	container: undefined,
+	container: htmlElement,
 	grid: grid
 }));
 
 grid.setActiveCell(0, 0);
 grid.editActiveCell(new Slick.Editors.Date<MyData>({
 	column: cols[0],
-	container: undefined,
+	container: htmlElement,
 	grid: grid
 }));
 
@@ -203,7 +205,8 @@ columns.forEach(column => {
 });
 
 grid.onSort.subscribe((e, args) => {
-    var sortCol:string = args.sortCols[0].sortCol.field;
+    if (!args.sortCols) return;
+    var sortCol: string | undefined = args.sortCols[0].sortCol.field;
 });
 
 grid.onMouseEnter.subscribe((e: DOMEvent, args: Slick.OnMouseEnterEventArgs<MyData>) => {
diff --git a/types/slickgrid/tsconfig.json b/types/slickgrid/tsconfig.json
index 4609f7987e..e5ccc104b9 100644
--- a/types/slickgrid/tsconfig.json
+++ b/types/slickgrid/tsconfig.json
@@ -7,7 +7,7 @@
         ],
         "noImplicitAny": true,
         "noImplicitThis": true,
-        "strictNullChecks": false,
+        "strictNullChecks": true,
         "strictFunctionTypes": true,
         "baseUrl": "../",
         "typeRoots": [
@@ -28,4 +28,4 @@
         "test/slick.autotooltips.ts",
         "test/slick.checkboxselectcolumn.ts"
     ]
-}
\ No newline at end of file
+}