diff --git a/filebeat/tests/system/test_modules.py b/filebeat/tests/system/test_modules.py
index 917f5809fff..37b199715a4 100644
--- a/filebeat/tests/system/test_modules.py
+++ b/filebeat/tests/system/test_modules.py
@@ -130,7 +130,8 @@ def run_on_file(self, module, fileset, test_file, cfgfile):
             "-c", cfgfile,
             "-modules={}".format(module),
             "-M", "{module}.*.enabled=false".format(module=module),
-            "-M", "{module}.{fileset}.enabled=true".format(module=module, fileset=fileset),
+            "-M", "{module}.{fileset}.enabled=true".format(
+                module=module, fileset=fileset),
             "-M", "{module}.{fileset}.var.paths=[{test_file}]".format(
                 module=module, fileset=fileset, test_file=test_file),
             "-M", "*.*.input.close_eof=true",
@@ -157,7 +158,8 @@ def run_on_file(self, module, fileset, test_file, cfgfile):
             assert obj["fileset"]["module"] == module, "expected fileset.module={} but got {}".format(
                 module, obj["fileset"]["module"])
 
-            assert "error" not in obj, "not error expected but got: {}".format(obj)
+            assert "error" not in obj, "not error expected but got: {}".format(
+                obj)
 
             if (module == "auditd" and fileset == "log") \
                     or (module == "osquery" and fileset == "result"):
@@ -248,13 +250,16 @@ def _run_ml_test(self, setup_flag, modules_flag):
         # Clean any previous state
         for df in self.es.transport.perform_request("GET", "/_xpack/ml/datafeeds/")["datafeeds"]:
             if df["datafeed_id"] == 'filebeat-nginx-access-response_code':
-                self.es.transport.perform_request("DELETE", "/_xpack/ml/datafeeds/" + df["datafeed_id"])
+                self.es.transport.perform_request(
+                    "DELETE", "/_xpack/ml/datafeeds/" + df["datafeed_id"])
 
         for df in self.es.transport.perform_request("GET", "/_xpack/ml/anomaly_detectors/")["jobs"]:
             if df["job_id"] == 'datafeed-filebeat-nginx-access-response_code':
-                self.es.transport.perform_request("DELETE", "/_xpack/ml/anomaly_detectors/" + df["job_id"])
+                self.es.transport.perform_request(
+                    "DELETE", "/_xpack/ml/anomaly_detectors/" + df["job_id"])
 
-        shutil.rmtree(os.path.join(self.working_dir, "modules.d"), ignore_errors=True)
+        shutil.rmtree(os.path.join(self.working_dir,
+                                   "modules.d"), ignore_errors=True)
 
         # generate a minimal configuration
         cfgfile = os.path.join(self.working_dir, "filebeat.yml")
@@ -322,5 +327,6 @@ def _run_ml_test(self, setup_flag, modules_flag):
 
         beat.kill()
 
+
 def pretty_json(obj):
-    return json.dumps(obj, indent=2, separators=(',',': '))
+    return json.dumps(obj, indent=2, separators=(',', ': '))