diff --git a/composer.json b/composer.json
index df3aaf2a..ca1243fc 100644
--- a/composer.json
+++ b/composer.json
@@ -42,8 +42,8 @@
         "ext-pcre": "*",
         "ext-spl": "*",
 
-        "simplesamlphp/assert": "^1.1",
-        "simplesamlphp/xml-common": "^1.15"
+        "simplesamlphp/assert": "dev-feature/xs-datetime-regex",
+        "simplesamlphp/xml-common": "dev-feature/xs-datetime-regex"
     },
     "require-dev": {
         "simplesamlphp/simplesamlphp-test-framework": "^1.5"