diff --git a/include/winternl.h b/include/winternl.h
index 0e23fdd97bf..5be28856920 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -4374,7 +4374,7 @@ NTSYSAPI NTSTATUS  WINAPI RtlLookupAtomInAtomTable(RTL_ATOM_TABLE,const WCHAR*,R
 NTSYSAPI NTSTATUS  WINAPI RtlMakeSelfRelativeSD(PSECURITY_DESCRIPTOR,PSECURITY_DESCRIPTOR,LPDWORD);
 NTSYSAPI void      WINAPI RtlMapGenericMask(PACCESS_MASK,const GENERIC_MAPPING*);
 NTSYSAPI NTSTATUS  WINAPI RtlMultiByteToUnicodeN(LPWSTR,DWORD,LPDWORD,LPCSTR,DWORD);
-NTSYSAPI NTSTATUS  WINAPI RtlMultiByteToUnicodeSize(DWORD*,LPCSTR,UINT);
+NTSYSAPI NTSTATUS  WINAPI RtlMultiByteToUnicodeSize(DWORD*,LPCSTR,ULONG);
 NTSYSAPI NTSTATUS  WINAPI RtlNewSecurityObject(PSECURITY_DESCRIPTOR,PSECURITY_DESCRIPTOR,PSECURITY_DESCRIPTOR*,BOOLEAN,HANDLE,PGENERIC_MAPPING);
 NTSYSAPI PRTL_USER_PROCESS_PARAMETERS WINAPI RtlNormalizeProcessParams(RTL_USER_PROCESS_PARAMETERS*);
 NTSYSAPI NTSTATUS  WINAPI RtlNormalizeString(ULONG,const WCHAR*,INT,WCHAR*,INT*);
@@ -4382,7 +4382,7 @@ NTSYSAPI ULONG     WINAPI RtlNtStatusToDosError(NTSTATUS);
 NTSYSAPI ULONG     WINAPI RtlNtStatusToDosErrorNoTeb(NTSTATUS);
 NTSYSAPI ULONG     WINAPI RtlNumberOfSetBits(PCRTL_BITMAP);
 NTSYSAPI ULONG     WINAPI RtlNumberOfClearBits(PCRTL_BITMAP);
-NTSYSAPI UINT      WINAPI RtlOemStringToUnicodeSize(const STRING*);
+NTSYSAPI ULONG     WINAPI RtlOemStringToUnicodeSize(const STRING*);
 NTSYSAPI NTSTATUS  WINAPI RtlOemStringToUnicodeString(UNICODE_STRING*,const STRING*,BOOLEAN);
 NTSYSAPI NTSTATUS  WINAPI RtlOemToUnicodeN(LPWSTR,DWORD,LPDWORD,LPCSTR,DWORD);
 NTSYSAPI NTSTATUS  WINAPI RtlOpenCurrentUser(ACCESS_MASK,PHANDLE);