diff --git a/composer.json b/composer.json
index f15ff4bdfec6a23ed2d43bd1cd7ae78710ce60f9..cea553ebfe8d9aeca041d8079c4db005b9fee94f 100644
--- a/composer.json
+++ b/composer.json
@@ -50,7 +50,7 @@
         "opis/json-schema": "^1.0",
         "slim/psr7": "1.4",
         "slim/slim": "4.7.1",
-        "php-di/php-di": "6.3.4",
+        "php-di/php-di": "^6.3.4",
         "symfony/console": "~5.3.16",
         "symfony/process": "^5.4",
         "jumbojett/openid-connect-php": "^0.9.2",
diff --git a/composer.lock b/composer.lock
index 3e332d2b57ff5e992dfbeca0b65b98c63be60dd4..979df2a5e256330f9c84878225fbe772da5a1b66 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "09395db276863ae31a0b9e4de81ab3e2",
+    "content-hash": "3e4a84c4dabcd0e37a213bb530baa1e1",
     "packages": [
         {
             "name": "algo26-matthias/idna-convert",
@@ -1895,16 +1895,16 @@
         },
         {
             "name": "php-di/php-di",
-            "version": "6.3.4",
+            "version": "6.3.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHP-DI/PHP-DI.git",
-                "reference": "f53bcba06ab31b18e911b77c039377f4ccd1f7a5"
+                "reference": "b8126d066ce144765300ee0ab040c1ed6c9ef588"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHP-DI/PHP-DI/zipball/f53bcba06ab31b18e911b77c039377f4ccd1f7a5",
-                "reference": "f53bcba06ab31b18e911b77c039377f4ccd1f7a5",
+                "url": "https://api.github.com/repos/PHP-DI/PHP-DI/zipball/b8126d066ce144765300ee0ab040c1ed6c9ef588",
+                "reference": "b8126d066ce144765300ee0ab040c1ed6c9ef588",
                 "shasum": ""
             },
             "require": {
@@ -1955,7 +1955,7 @@
             ],
             "support": {
                 "issues": "https://github.com/PHP-DI/PHP-DI/issues",
-                "source": "https://github.com/PHP-DI/PHP-DI/tree/6.3.4"
+                "source": "https://github.com/PHP-DI/PHP-DI/tree/6.3.5"
             },
             "funding": [
                 {
@@ -1967,7 +1967,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-06-10T08:04:48+00:00"
+            "time": "2021-09-02T09:49:58+00:00"
         },
         {
             "name": "php-di/phpdoc-reader",