diff --git a/routlin/install.py b/routlin/install.py
index 105abb8..c9780cc 100644
--- a/routlin/install.py
+++ b/routlin/install.py
@@ -192,6 +192,7 @@ def install_core_packages(pm):
 
     if not missing:
         print("  All required packages are already installed.")
+        fix_freeradius_service_file()
         return
 
     print("  The following packages are not installed:")
@@ -210,6 +211,19 @@ def install_core_packages(pm):
         die("Package installation failed. Install manually and retry.")
 
     print("\n  Core packages installed.")
+    fix_freeradius_service_file()
+
+
+def fix_freeradius_service_file():
+    svc = Path("/lib/systemd/system/freeradius.service")
+    if not svc.exists():
+        return
+    text = svc.read_text()
+    if "MemoryLimit=" not in text:
+        return
+    svc.write_text(text.replace("MemoryLimit=", "MemoryMax="))
+    subprocess.run(["systemctl", "daemon-reload"], capture_output=True, text=True)
+    print("  Fixed deprecated MemoryLimit= in freeradius.service (replaced with MemoryMax=).")
 
 
 # ===================================================================