diff --git a/src/port/win32security.c b/src/port/win32security.c
index 2c9ca15..e329eb0 100644
--- a/src/port/win32security.c
+++ b/src/port/win32security.c
@@ -122,12 +122,9 @@ pgwin32_is_admin(void)
 }

 /*
- * We consider ourselves running as a service if one of the following is
- * true:
- *
- * 1) We are running as Local System (only used by services)
- * 2) Our token contains SECURITY_SERVICE_RID (automatically added to the
- *	  process token by the SCM when starting a service)
+ * We consider ourselves running as a service if our token contains
+ * SECURITY_SERVICE_RID, which is automatically added to the process token
+ * by the SCM when starting a service.
  *
  * Return values:
  *	 0 = Not service
@@ -147,9 +144,7 @@ pgwin32_is_service(void)
 	char	   *InfoBuffer = NULL;
 	char		errbuf[256];
 	PTOKEN_GROUPS Groups;
-	PTOKEN_USER User;
 	PSID		ServiceSid;
-	PSID		LocalSystemSid;
 	SID_IDENTIFIER_AUTHORITY NtAuthority = {SECURITY_NT_AUTHORITY};
 	UINT		x;

@@ -164,37 +159,6 @@ pgwin32_is_service(void)
 		return -1;
 	}

-	/* First check for local system */
-	if (!pgwin32_get_dynamic_tokeninfo(AccessToken, TokenUser, &InfoBuffer,
-									   errbuf, sizeof(errbuf)))
-	{
-		fprintf(stderr, "%s", errbuf);
-		return -1;
-	}
-
-	User = (PTOKEN_USER) InfoBuffer;
-
-	if (!AllocateAndInitializeSid(&NtAuthority, 1,
-							  SECURITY_LOCAL_SYSTEM_RID, 0, 0, 0, 0, 0, 0, 0,
-								  &LocalSystemSid))
-	{
-		fprintf(stderr, "could not get SID for local system account\n");
-		CloseHandle(AccessToken);
-		return -1;
-	}
-
-	if (EqualSid(LocalSystemSid, User->User.Sid))
-	{
-		FreeSid(LocalSystemSid);
-		free(InfoBuffer);
-		CloseHandle(AccessToken);
-		_is_service = 1;
-		return _is_service;
-	}
-
-	FreeSid(LocalSystemSid);
-	free(InfoBuffer);
-
 	/* Now check for group SID */
 	if (!pgwin32_get_dynamic_tokeninfo(AccessToken, TokenGroups, &InfoBuffer,
 									   errbuf, sizeof(errbuf)))
@@ -218,7 +182,8 @@ pgwin32_is_service(void)
 	_is_service = 0;
 	for (x = 0; x < Groups->GroupCount; x++)
 	{
-		if (EqualSid(ServiceSid, Groups->Groups[x].Sid))
+		if (EqualSid(ServiceSid, Groups->Groups[x].Sid) &&
+			(Groups->Groups[x].Attributes & SE_GROUP_ENABLED))
 		{
 			_is_service = 1;
 			break;