diff --git a/gap-digraphs.spec b/gap-digraphs.spec
index e89fdbd..bc5af90 100644
--- a/gap-digraphs.spec
+++ b/gap-digraphs.spec
@@ -24,7 +24,7 @@ License:        GPL-3.0+
 Group:          Productivity/Scientific/Math
 Url:            http://www-groups.mcs.st-andrews.ac.uk/~jamesm/digraphs.php
 
-Source:         http://www.gap-system.org/pub/gap/gap4/tar.bz2/packages/digraphs-%version.tar.bz2
+Source:         https://www.gap-system.org/pub/gap/gap4/tar.bz2/packages/digraphs-%version.tar.bz2
 BuildRequires:  fdupes
 BuildRequires:  gap-devel
 BuildRequires:  gap-rpm-devel