diff --git a/perun/proxy/utils/nagios/check_php_syntax.py b/perun/proxy/utils/nagios/check_php_syntax.py
index 56d0efe0c1202cde1c027995c44be490b22992ce..c0651be9a062d86d95992baf6a40ccbe475aac57 100755
--- a/perun/proxy/utils/nagios/check_php_syntax.py
+++ b/perun/proxy/utils/nagios/check_php_syntax.py
@@ -1,6 +1,5 @@
 #!/usr/bin/env python3
 
-import os
 import subprocess
 import sys
 import argparse
@@ -20,39 +19,42 @@ def get_args():
             " automatically generated files"
         )
     )
+    parser.add_argument(
+        "-c",
+        "--container",
+        required=True,
+        help="Docker container name to run PHP syntax check inside",
+    )
     parser.add_argument(
         "-d",
         "--directory",
         required=True,
-        help="path which will be scanned for PHP files, including subdirectories",
+        help=(
+            "path inside container which will be scanned for PHP files, including"
+            " subdirectories"
+        ),
     )
     return parser.parse_args()
 
 
 def main():
-    dir = get_args().directory
-    os.chdir(dir)
-    paths = []
-    for (
-        dirpath,
-        dirname,
-        filenames,
-    ) in os.walk("."):
-        for f in filenames:
-            if f.endswith(".php"):
-                paths.append(
-                    os.path.join(
-                        dirpath,
-                        f,
-                    )
-                )
+    args = get_args()
+    dir = args.directory
+    container = args.container
+
+    container_paths = (
+        subprocess.getoutput(
+            f"docker exec {container} find {dir} -type f -name '*.php'"
+        )
+        .strip()
+        .split("\n")
+    )
     global_result = ""
 
-    for path in paths:
-        if os.path.isfile(path):
-            result = subprocess.getoutput(f"php -l {path}")
-            if not result.startswith("No syntax errors"):
-                global_result += f"{result}  |  "
+    for path in container_paths:
+        result = subprocess.getoutput(f"docker exec {container} php -l {path}")
+        if "No syntax errors" not in result:
+            global_result += f"{result}  |  "
 
     if not global_result:
         print(f"{OK} check_php_syntax - OK")