diff --git a/tools/sigma/backends/sysmon.py b/tools/sigma/backends/sysmon.py
index 852bd1739..3b592525b 100644
--- a/tools/sigma/backends/sysmon.py
+++ b/tools/sigma/backends/sysmon.py
@@ -217,7 +217,7 @@ class SysmonConfigBackend(SingleTextQueryBackend, MultiRuleOutputMixin):
             raise NotSupportedError(
                 "Not supported logsource. Should be product `windows`.")
         for item in self.logsource.values():
-             if str(item).lower() in self.allowedSource.keys():
+            if str(item).lower() in self.allowedSource.keys():
                 self.table = self.allowedSource.get(item.lower())
                 break
         else: