diff --git a/types/d3-contour/d3-contour-tests.ts b/types/d3-contour/d3-contour-tests.ts
index ce9d50717f..48f8508d01 100644
--- a/types/d3-contour/d3-contour-tests.ts
+++ b/types/d3-contour/d3-contour-tests.ts
@@ -113,7 +113,10 @@ interface CustomDatum {
 
 // Get contour generator -------------------------------------------------------
 
-const contDensDefault: d3Contour.ContourDensity<[number, number]> = d3Contour.contourDensity();
+// test generic parameter defaults for ContourDensity and contourDensity
+const contDensDefault: d3Contour.ContourDensity = d3Contour.contourDensity();
+const contDensDefaultCopy: d3Contour.ContourDensity<[number, number]> = contDensDefault;
+// test with explicit generic parameter
 let contDensCustom: d3Contour.ContourDensity<CustomDatum> = d3Contour.contourDensity<CustomDatum>();
 
 // Configure contour generator =================================================
diff --git a/types/d3-contour/index.d.ts b/types/d3-contour/index.d.ts
index ba9c8e075d..c0b3d70b5e 100644
--- a/types/d3-contour/index.d.ts
+++ b/types/d3-contour/index.d.ts
@@ -120,8 +120,13 @@ export function contours(): Contours;
 
 /**
  * A contour generator for density estimates.
+ *
+ * The generic refers to the data type of an element in the data array
+ * used with the density contour generator. If omitted, the default setting assumes that,
+ * the elements of the data array used with the density contour generator are two-element arrays.
+ * The first element corresponds to the x-dimension, the second to the y-dimension.
  */
-export interface ContourDensity<Datum> {
+export interface ContourDensity<Datum = [number, number]> {
     /**
      * Estimates the density contours for the given array of data, returning an array of GeoJSON MultiPolygon geometry objects.
      * Each geometry object represents the area where the estimated number of points per square pixel is greater than or equal to
@@ -238,21 +243,15 @@ export interface ContourDensity<Datum> {
     bandwidth(bandwidth: number): this;
 }
 
-/**
- * Construct a new contour generator for density estimates with the default settings.
- *
- * The default settings assume that, the elements of the data array used
- * with the density contour generator are two-element arrays. The first element
- * corresponds to the x-dimension, the second to the y-dimension.
- */
-export function contourDensity(): ContourDensity<[number, number]>;
 /**
  * Construct a new contour generator for density estimates.
  *
  * The generic refers to the data type of an element in the data array
- * used with the density contour generator.
+ * used with the density contour generator. If omitted, the default setting assumes that,
+ * the elements of the data array used with the density contour generator are two-element arrays.
+ * The first element corresponds to the x-dimension, the second to the y-dimension.
  *
  * Important: ensure that the x- and y-accessor functions are configured to
  * match the data type used for the generic Datum.
  */
-export function contourDensity<Datum>(): ContourDensity<Datum>;
+export function contourDensity<Datum = [number, number]>(): ContourDensity<Datum>;