diff --git a/reactos/include/winternl.h b/reactos/include/winternl.h
index 368fe1fc0bb..4fbf08d5fcf 100644
--- a/reactos/include/winternl.h
+++ b/reactos/include/winternl.h
@@ -1985,7 +1985,7 @@ BOOL      WINAPI RtlEqualPrefixSid(PSID,PSID);
 BOOL      WINAPI RtlEqualSid(PSID,PSID);
 BOOLEAN   WINAPI RtlEqualString(const STRING*,const STRING*,BOOLEAN);
 BOOLEAN   WINAPI RtlEqualUnicodeString(const UNICODE_STRING*,const UNICODE_STRING*,BOOLEAN);
-//void      WINAPI RtlExitUserThread(ULONG) DECLSPEC_NORETURN;
+void      WINAPI RtlExitUserThread(ULONG) DECLSPEC_NORETURN;
 NTSTATUS  WINAPI RtlExpandEnvironmentStrings_U(PWSTR, const UNICODE_STRING*, UNICODE_STRING*, ULONG*);
 LONGLONG  WINAPI RtlExtendedMagicDivide(LONGLONG,LONGLONG,INT);
 LONGLONG  WINAPI RtlExtendedIntegerMultiply(LONGLONG,INT);