diff --git a/openlayers/index.d.ts b/openlayers/index.d.ts
index a70f3b115b..2c0367e7b7 100644
--- a/openlayers/index.d.ts
+++ b/openlayers/index.d.ts
@@ -4495,7 +4495,7 @@ declare namespace ol {
         /**
          * A function that takes an ol.Feature and a {number} representing the view's resolution. The function should return an array of ol.style.Style. This way e.g. a vector layer can be styled.
          */
-        interface StyleFunction { (feature: ol.Feature, resolution: number): ol.style.Style }
+        interface StyleFunction { (feature: ol.Feature, resolution: number): ol.style.Style | ol.style.Style[] }
     }
 
     namespace tilegrid {
diff --git a/openlayers/openlayers-3.14.2-tests.ts b/openlayers/openlayers-3.14.2-tests.ts
index 1bfdc4bf63..69c44b82d6 100644
--- a/openlayers/openlayers-3.14.2-tests.ts
+++ b/openlayers/openlayers-3.14.2-tests.ts
@@ -685,6 +685,16 @@ draw = new ol.interaction.Draw({
     type: "Point",
     style: styleFunction
 });
+var styleFunctionAsStyle = function(feature: ol.Feature, resolution: number): ol.style.Style { return style; }
+draw = new ol.interaction.Draw({
+    type: "Point",
+    style: styleFunctionAsStyle
+});
+var styleFunctionAsArray = function(feature: ol.Feature, resolution: number): ol.style.Style[] { return styleArray; }
+draw = new ol.interaction.Draw({
+    type: "Point",
+    style: styleFunctionAsArray
+});
 
 var dragbox: ol.interaction.DragBox = new ol.interaction.DragBox({
     className: stringValue,
diff --git a/openlayers/openlayers-3.14.2.d.ts b/openlayers/openlayers-3.14.2.d.ts
index 5046e1fa8f..23b25f8a2e 100644
--- a/openlayers/openlayers-3.14.2.d.ts
+++ b/openlayers/openlayers-3.14.2.d.ts
@@ -4651,7 +4651,7 @@ declare namespace ol {
         /**
          * A function that takes an ol.Feature and a {number} representing the view's resolution. The function should return an array of ol.style.Style. This way e.g. a vector layer can be styled.
          */
-        interface StyleFunction { (feature: ol.Feature, resolution: number): ol.style.Style }
+        interface StyleFunction { (feature: ol.Feature, resolution: number): ol.style.Style | ol.style.Style[] }
     }
 
     namespace tilegrid {