diff --git a/debian/changelog b/debian/changelog
index 6a7739a..405e629 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,6 +1,7 @@
 votca-xtp (1.6.4-2) UNRELEASED; urgency=medium
 
   * Trim trailing whitespace.
+  * Use secure copyright file specification URI.
 
  -- Debian Janitor <janitor@jelmer.uk>  Sat, 06 Mar 2021 18:45:29 -0000
 
diff --git a/debian/copyright b/debian/copyright
index 6966e3c..5c92b42 100644
--- a/debian/copyright
+++ b/debian/copyright
@@ -1,4 +1,4 @@
-Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 Upstream-Name: votca-xtp
 Source: https://github.com/votca/xtp/releases