diff --git a/.fixtures.yml b/.fixtures.yml
index ef1ab41..91f2745 100644
--- a/.fixtures.yml
+++ b/.fixtures.yml
@@ -2,9 +2,9 @@ fixtures:
   forge_modules:
     stdlib:
       repo: puppetlabs-stdlib
-      ref: 4.11.0
+      ref: 4.25.1
     concat:
       repo: puppetlabs-concat
-      ref: 2.1.0
+      ref: 5.1.0
   symlinks:
     "tsm": "#{source_dir}"
diff --git a/metadata.json b/metadata.json
index 89aecae..4fdbb92 100644
--- a/metadata.json
+++ b/metadata.json
@@ -79,7 +79,7 @@
     },
     {
       "name": "puppetlabs/concat",
-      "version_requirement": ">=1.1.0 <3.0.0"
+      "version_requirement": ">=1.1.0 <6.0.0"
     }
   ]
 }