diff --git a/types/jquery/index.d.ts b/types/jquery/index.d.ts
index a8b2895d6b..cedea8354e 100644
--- a/types/jquery/index.d.ts
+++ b/types/jquery/index.d.ts
@@ -699,6 +699,14 @@ interface JQueryCoordinates {
     top: number;
 }
 
+/**
+ * The interface used to specify the properties parameter in css()
+ */
+type cssPropertySetter = (index: number, value?: string) => string | number;
+interface JQueryCssProperties {
+	[propertyName: string]: string | number | cssPropertySetter;
+}
+
 /**
  * Elements in the array returned by serializeArray()
  */
@@ -1707,7 +1715,7 @@ interface JQuery {
      * @param properties An object of property-value pairs to set.
      * @see {@link https://api.jquery.com/css/#css-properties}
      */
-    css(properties: Object): JQuery;
+    css(properties: JQueryCssProperties): JQuery;
 
     /**
      * Get the current computed height for the first element in the set of matched elements.
diff --git a/types/jquery/jquery-tests.ts b/types/jquery/jquery-tests.ts
index d2d58aa2a2..4b6fc4e0db 100644
--- a/types/jquery/jquery-tests.ts
+++ b/types/jquery/jquery-tests.ts
@@ -1065,6 +1065,9 @@ function test_css() {
     $('div.example').css('width', function (index) {
         return index * 50;
     });
+    $('div.example').css('width', function (index, style) {
+        return style.length > 0 ? style : index * 50;
+    });
     $("p").mouseover(function () {
         $(this).css("color", "red");
     });