diff --git a/types/openlayers/index.d.ts b/types/openlayers/index.d.ts
index 3d62c4262c..c2e7ab1530 100644
--- a/types/openlayers/index.d.ts
+++ b/types/openlayers/index.d.ts
@@ -5,6 +5,7 @@
 //                 Junyoung Clare Jang <https://github.com/ailrun>
 //                 Alexandre Melard <https://github.com/mylen>
 //                 Chad Johnston <https://github.com/iamthechad>
+//                 Dan Manastireanu <https://github.com/danmana>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // Definitions partially generated using tsd-jsdoc (https://github.com/englercj/tsd-jsdoc)
 
@@ -14042,7 +14043,7 @@ declare module olx {
             hidpi?: boolean;
             logo?: (string | olx.LogoOptions);
             tileGrid?: ol.tilegrid.TileGrid;
-            projection: ol.ProjectionLike;
+            projection?: ol.ProjectionLike;
             reprojectionErrorThreshold?: number;
             serverType?: (ol.source.wms.ServerType | string);
             tileLoadFunction?: ol.TileLoadFunctionType;
diff --git a/types/openlayers/openlayers-tests.ts b/types/openlayers/openlayers-tests.ts
index 26e0d391fc..666b7b746f 100644
--- a/types/openlayers/openlayers-tests.ts
+++ b/types/openlayers/openlayers-tests.ts
@@ -558,6 +558,12 @@ let tileWMS: ol.source.TileWMS = new ol.source.TileWMS({
     url: stringValue
 });
 
+//test without projection
+tileWMS = new ol.source.TileWMS({
+    params: {},
+    serverType: stringValue,
+    url: stringValue
+});
 voidValue = tileWMS.updateParams(tileWMS.getParams());
 stringValue = tileWMS.getGetFeatureInfoUrl([0, 0], 1, "EPSG:4326", {});