diff --git a/dist/index.js b/dist/index.js
index 47fed43..3ca1470 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -62113,8 +62113,8 @@ function processAdditionalRegistries(targetRegistries) {
     const additionalRegistriesArr = additionalRegistries.split(',');
     for (let registry of additionalRegistriesArr) {
       registry = registry.trim();
-      if (registry.endsWith(':')) {
-        registry = registry.substring(0, registry.length - 1);
+      if (!registry.contains(':')) {
+        registry += ':';
       }
       targetRegistries.push(registry);
     }
@@ -62220,7 +62220,7 @@ function prepareDestinations(registries, tags) {
   const destinations = [];
   registries.forEach((registry) => {
     tags.forEach((tag) => {
-      destinations.push(registry + ':' + tag);
+      destinations.push(registry + tag);
     });
   });
 
@@ -62336,7 +62336,7 @@ try {
 
   let ci_registry = false;
   if (core.getBooleanInput('add_ci_registry_target')) {
-    ci_registry = information.ci_hostname + '/' + repoStr;
+    ci_registry = information.ci_hostname + '/' + repoStr + ':';
     targetRegistries.push(ci_registry);
   }
 
diff --git a/src/action.js b/src/action.js
index 2316bb3..b1e8b1b 100644
--- a/src/action.js
+++ b/src/action.js
@@ -3,9 +3,11 @@ import * as github from '@actions/github';
 import * as action_information from 'information';
 import {
   addCiRegistryAuth,
-  collectTags, executeDockerBuild,
+  collectTags,
+  executeDockerBuild,
   mergeArgRegistryAuthJson,
-  prepareDestinations, prepareDockerArgs,
+  prepareDestinations,
+  prepareDockerArgs,
   processAdditionalRegistries,
   writeRegistryAuthJson
 } from './lib';
@@ -22,7 +24,7 @@ try {
 
   let ci_registry = false;
   if (core.getBooleanInput('add_ci_registry_target')) {
-    ci_registry = information.ci_hostname + '/' + repoStr;
+    ci_registry = information.ci_hostname + '/' + repoStr + ':';
     targetRegistries.push(ci_registry);
   }
 
diff --git a/src/lib.js b/src/lib.js
index 2b64e61..e042889 100644
--- a/src/lib.js
+++ b/src/lib.js
@@ -11,8 +11,8 @@ export function processAdditionalRegistries(targetRegistries) {
     const additionalRegistriesArr = additionalRegistries.split(',');
     for (let registry of additionalRegistriesArr) {
       registry = registry.trim();
-      if (registry.endsWith(':')) {
-        registry = registry.substring(0, registry.length - 1);
+      if (!registry.contains(':')) {
+        registry += ':';
       }
       targetRegistries.push(registry);
     }
@@ -118,7 +118,7 @@ export function prepareDestinations(registries, tags) {
   const destinations = [];
   registries.forEach((registry) => {
     tags.forEach((tag) => {
-      destinations.push(registry + ':' + tag);
+      destinations.push(registry + tag);
     });
   });