diff --git a/dlls/advapi32/crypt_md4.c b/dlls/advapi32/crypt_md4.c
index 066f1d5c7fa..5f4e7093f5f 100644
--- a/dlls/advapi32/crypt_md4.c
+++ b/dlls/advapi32/crypt_md4.c
@@ -285,12 +285,12 @@ static void MD4Transform( unsigned int buf[4], const unsigned int in[16] )
  *  Failure: STATUS_UNSUCCESSFUL
  *
  */
-NTSTATUS WINAPI SystemFunction007(PUNICODE_STRING string, LPBYTE hash)
+NTSTATUS WINAPI SystemFunction007(const UNICODE_STRING *string, LPBYTE hash)
 {
     MD4_CTX ctx;
 
     MD4Init( &ctx );
-    MD4Update( &ctx, (BYTE*) string->Buffer, string->Length );
+    MD4Update( &ctx, (const BYTE *)string->Buffer, string->Length );
     MD4Final( &ctx );
     memcpy( hash, ctx.digest, 0x10 );
 
@@ -313,7 +313,7 @@ NTSTATUS WINAPI SystemFunction007(PUNICODE_STRING string, LPBYTE hash)
  *  Failure: STATUS_UNSUCCESSFUL
  *
  */
-NTSTATUS WINAPI SystemFunction010(LPVOID unknown, LPBYTE data, LPBYTE hash)
+NTSTATUS WINAPI SystemFunction010(LPVOID unknown, const BYTE *data, LPBYTE hash)
 {
     MD4_CTX ctx;
 
diff --git a/dlls/advapi32/tests/crypt_md4.c b/dlls/advapi32/tests/crypt_md4.c
index a114089d2d3..48ee0b9c777 100644
--- a/dlls/advapi32/tests/crypt_md4.c
+++ b/dlls/advapi32/tests/crypt_md4.c
@@ -39,7 +39,7 @@ typedef struct
 typedef VOID (WINAPI *fnMD4Init)( MD4_CTX *ctx );
 typedef VOID (WINAPI *fnMD4Update)( MD4_CTX *ctx, const unsigned char *src, const int len );
 typedef VOID (WINAPI *fnMD4Final)( MD4_CTX *ctx );
-typedef int (WINAPI *fnSystemFunction007)(PUNICODE_STRING,LPBYTE);
+typedef int (WINAPI *fnSystemFunction007)(const UNICODE_STRING *, LPBYTE);
 typedef int (WINAPI *md4hashfunc)(LPVOID, const LPBYTE, LPBYTE);
 
 fnMD4Init pMD4Init;