diff --git a/README.md b/README.md
index 3175bd9..ae9c742 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 [![Latest Release](https://img.shields.io/github/release/muesli/kmeans.svg)](https://github.com/muesli/kmeans/releases)
 [![Build Status](https://github.com/muesli/kmeans/workflows/build/badge.svg)](https://github.com/muesli/kmeans/actions)
 [![Coverage Status](https://coveralls.io/repos/github/muesli/kmeans/badge.svg?branch=master)](https://coveralls.io/github/muesli/kmeans?branch=master)
-[![Go ReportCard](http://goreportcard.com/badge/muesli/kmeans)](http://goreportcard.com/report/muesli/kmeans)
+[![Go ReportCard](https://goreportcard.com/badge/muesli/kmeans)](https://goreportcard.com/report/muesli/kmeans)
 [![GoDoc](https://godoc.org/github.com/golang/gddo?status.svg)](https://pkg.go.dev/github.com/muesli/kmeans)
 
 k-means clustering algorithm implementation written in Go