diff --git a/packages/h5p-server/package-lock.json b/packages/h5p-server/package-lock.json
index 8c4a74419..a556de41f 100644
--- a/packages/h5p-server/package-lock.json
+++ b/packages/h5p-server/package-lock.json
@@ -15,7 +15,7 @@
                 "axios": "^1.4.0",
                 "cache-manager": "^4.0.0",
                 "debug": "^4.3.4",
-                "flat": "^5.0.2",
+                "flat": "^6.0.0",
                 "fs-extra": "^11.1.1",
                 "get-all-files": "^4.1.0",
                 "https-proxy-agent": "^5.0.1",
@@ -891,12 +891,15 @@
             }
         },
         "node_modules/flat": {
-            "version": "5.0.2",
-            "resolved": "https://registry.npmjs.org/flat/-/flat-5.0.2.tgz",
-            "integrity": "sha512-b6suED+5/3rTpUBdG1gupIl8MPFCAMA0QXwmljLhvCUKcUvdE4gWky9zpuGCcXHOsz4J9wPGNWq6OKpmIzz3hQ==",
+            "version": "6.0.1",
+            "resolved": "https://registry.npmjs.org/flat/-/flat-6.0.1.tgz",
+            "integrity": "sha512-/3FfIa8mbrg3xE7+wAhWeV+bd7L2Mof+xtZb5dRDKZ+wDvYJK4WDYeIOuOhre5Yv5aQObZrlbRmk3RTSiuQBtw==",
             "license": "BSD-3-Clause",
             "bin": {
                 "flat": "cli.js"
+            },
+            "engines": {
+                "node": ">=18"
             }
         },
         "node_modules/follow-redirects": {
diff --git a/packages/h5p-server/package.json b/packages/h5p-server/package.json
index ad83fcfe9..efc02158e 100644
--- a/packages/h5p-server/package.json
+++ b/packages/h5p-server/package.json
@@ -51,7 +51,7 @@
         "axios": "^1.4.0",
         "cache-manager": "^4.0.0",
         "debug": "^4.3.4",
-        "flat": "^5.0.2",
+        "flat": "^6.0.0",
         "fs-extra": "^11.1.1",
         "get-all-files": "^4.1.0",
         "https-proxy-agent": "^5.0.1",