diff --git a/reactos/dll/win32/advapi32/sec/sid.c b/reactos/dll/win32/advapi32/sec/sid.c
index 1b950be8cde..7148647e425 100644
--- a/reactos/dll/win32/advapi32/sec/sid.c
+++ b/reactos/dll/win32/advapi32/sec/sid.c
@@ -1499,6 +1499,7 @@ WINAPI
 GetSidSubAuthority(PSID pSid,
                    DWORD nSubAuthority)
 {
+    SetLastError(ERROR_SUCCESS);
     return (PDWORD)RtlSubAuthoritySid(pSid, nSubAuthority);
 }
 
@@ -1510,6 +1511,7 @@ PUCHAR
 WINAPI
 GetSidSubAuthorityCount(PSID pSid)
 {
+    SetLastError(ERROR_SUCCESS);
     return RtlSubAuthorityCountSid(pSid);
 }