diff --git a/lib/config/definitions.js b/lib/config/definitions.js
index 5619c2494d580859dc74cb998d692e5fe5f2e87d..7ff890f0af7f3cc9bf3d20c1914ed28bed68dfb8 100644
--- a/lib/config/definitions.js
+++ b/lib/config/definitions.js
@@ -1041,7 +1041,8 @@ const options = [
         branchTopic: '{{{depNameSanitized}}}-{{{currentValue}}}',
         commitMessageExtra: 'to {{newDigestShort}}',
         prBody: template('prBody', 'docker-digest'),
-        commitMessageTopic: '{{{depName}}}:{{{currentValue}}} Docker digest',
+        commitMessageTopic:
+          '{{{depName}}}{{#if currentValue}}:{{{currentValue}}}{{/if}} Docker digest',
         group: {
           prBody: template('prBody', 'docker-digest-group'),
           commitMessageTopic: '{{{groupName}}}',