diff --git a/CHANGELOG.md b/CHANGELOG.md
index ddadc4d..74bf5bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## NOT RELEASED
 
+### Added
+
+- AWS api-change: Added `us-isof-east-1` and `us-isof-south-1` regions
+
 ## 1.2.4
 
 ### Changed
diff --git a/composer.json b/composer.json
index a8da47e..94a4e69 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.2-dev"
+            "dev-master": "1.3-dev"
         }
     }
 }
diff --git a/src/ElastiCacheClient.php b/src/ElastiCacheClient.php
index 722c967..3e63060 100644
--- a/src/ElastiCacheClient.php
+++ b/src/ElastiCacheClient.php
@@ -127,6 +127,14 @@ protected function getEndpointMetadata(?string $region): array
                     'signService' => 'elasticache',
                     'signVersions' => ['v4'],
                 ];
+            case 'us-isof-east-1':
+            case 'us-isof-south-1':
+                return [
+                    'endpoint' => "https://elasticache.$region.csp.hci.ic.gov",
+                    'signRegion' => $region,
+                    'signService' => 'elasticache',
+                    'signVersions' => ['v4'],
+                ];
             case 'us-isob-east-1':
                 return [
                     'endpoint' => 'https://elasticache.us-isob-east-1.sc2s.sgov.gov',