diff --git a/reactos/include/ndk/rtlfuncs.h b/reactos/include/ndk/rtlfuncs.h
index 2109349036b..6ac1f039427 100644
--- a/reactos/include/ndk/rtlfuncs.h
+++ b/reactos/include/ndk/rtlfuncs.h
@@ -1201,7 +1201,7 @@ NTSTATUS
 NTAPI
 RtlOemStringToUnicodeString(
     PUNICODE_STRING DestinationString,
-    POEM_STRING SourceString,
+    PCOEM_STRING SourceString,
     BOOLEAN AllocateDestinationString
 );