diff --git a/dlls/ntdll/ntdll.spec b/dlls/ntdll/ntdll.spec
index 01c84c6aa97..a7256c452ef 100644
--- a/dlls/ntdll/ntdll.spec
+++ b/dlls/ntdll/ntdll.spec
@@ -464,7 +464,8 @@
 @ stdcall RtlCompareMemory(ptr ptr long)
 @ stdcall RtlCompareMemoryUlong(ptr long long)
 @ stdcall RtlCompareString(ptr ptr long)
-@ stdcall RtlCompareUnicodeString (ptr ptr long)
+@ stdcall RtlCompareUnicodeString(ptr ptr long)
+@ stdcall RtlCompareUnicodeStrings(ptr long ptr long long)
 @ stdcall RtlCompressBuffer(long ptr long ptr long long ptr ptr)
 @ stdcall RtlComputeCrc32(long ptr long)
 # @ stub RtlComputeImportTableHash
diff --git a/dlls/ntdll/rtlstr.c b/dlls/ntdll/rtlstr.c
index 01b4446b168..3013658e596 100644
--- a/dlls/ntdll/rtlstr.c
+++ b/dlls/ntdll/rtlstr.c
@@ -451,30 +451,36 @@ LONG WINAPI RtlCompareString( const STRING *s1, const STRING *s2, BOOLEAN CaseIn
 }
 
 
+/******************************************************************************
+ *	RtlCompareUnicodeStrings   (NTDLL.@)
+ */
+LONG WINAPI RtlCompareUnicodeStrings( const WCHAR *s1, SIZE_T len1, const WCHAR *s2, SIZE_T len2,
+                                      BOOLEAN case_insensitive )
+{
+    LONG ret = 0;
+    SIZE_T len = min( len1, len2 );
+
+    if (case_insensitive)
+    {
+        while (!ret && len--) ret = toupperW(*s1++) - toupperW(*s2++);
+    }
+    else
+    {
+        while (!ret && len--) ret = *s1++ - *s2++;
+    }
+    if (!ret) ret = len1 - len2;
+    return ret;
+}
+
+
 /******************************************************************************
  *	RtlCompareUnicodeString   (NTDLL.@)
  */
 LONG WINAPI RtlCompareUnicodeString( const UNICODE_STRING *s1, const UNICODE_STRING *s2,
                                      BOOLEAN CaseInsensitive )
 {
-    unsigned int len;
-    LONG ret = 0;
-    LPCWSTR p1, p2;
-
-    len = min(s1->Length, s2->Length) / sizeof(WCHAR);
-    p1 = s1->Buffer;
-    p2 = s2->Buffer;
-
-    if (CaseInsensitive)
-    {
-        while (!ret && len--) ret = toupperW(*p1++) - toupperW(*p2++);
-    }
-    else
-    {
-        while (!ret && len--) ret = *p1++ - *p2++;
-    }
-    if (!ret) ret = s1->Length - s2->Length;
-    return ret;
+    return RtlCompareUnicodeStrings( s1->Buffer, s1->Length / sizeof(WCHAR),
+                                     s2->Buffer, s2->Length / sizeof(WCHAR), CaseInsensitive );
 }
 
 
diff --git a/dlls/ntdll/tests/rtlstr.c b/dlls/ntdll/tests/rtlstr.c
index dc27c3e6754..7f889dfa0d0 100644
--- a/dlls/ntdll/tests/rtlstr.c
+++ b/dlls/ntdll/tests/rtlstr.c
@@ -41,6 +41,8 @@ static NTSTATUS (WINAPI *pRtlAppendStringToString)(STRING *, const STRING *);
 static NTSTATUS (WINAPI *pRtlAppendUnicodeStringToString)(UNICODE_STRING *, const UNICODE_STRING *);
 static NTSTATUS (WINAPI *pRtlAppendUnicodeToString)(UNICODE_STRING *, LPCWSTR);
 static NTSTATUS (WINAPI *pRtlCharToInteger)(PCSZ, ULONG, int *);
+static LONG     (WINAPI *pRtlCompareUnicodeString)(const UNICODE_STRING*, const UNICODE_STRING*, BOOLEAN);
+static LONG     (WINAPI *pRtlCompareUnicodeStrings)(const WCHAR *,SIZE_T,const WCHAR *,SIZE_T,BOOLEAN);
 static VOID     (WINAPI *pRtlCopyString)(STRING *, const STRING *);
 static BOOLEAN  (WINAPI *pRtlCreateUnicodeString)(PUNICODE_STRING, LPCWSTR);
 static BOOLEAN  (WINAPI *pRtlCreateUnicodeStringFromAsciiz)(PUNICODE_STRING, LPCSTR);
@@ -75,7 +77,6 @@ static NTSTATUS (WINAPI *pRtlUTF8ToUnicodeN)(WCHAR *, ULONG, ULONG *, const CHAR
 /*static VOID (WINAPI *pRtlCopyUnicodeString)(UNICODE_STRING *, const UNICODE_STRING *);*/
 /*static VOID (WINAPI *pRtlEraseUnicodeString)(UNICODE_STRING *);*/
 /*static LONG (WINAPI *pRtlCompareString)(const STRING *,const STRING *,BOOLEAN);*/
-/*static LONG (WINAPI *pRtlCompareUnicodeString)(const UNICODE_STRING *,const UNICODE_STRING *,BOOLEAN);*/
 /*static BOOLEAN (WINAPI *pRtlEqualString)(const STRING *,const STRING *,BOOLEAN);*/
 /*static BOOLEAN (WINAPI *pRtlPrefixString)(const STRING *, const STRING *, BOOLEAN);*/
 /*static BOOLEAN (WINAPI *pRtlPrefixUnicodeString)(const UNICODE_STRING *, const UNICODE_STRING *, BOOLEAN);*/
@@ -112,6 +113,8 @@ static void InitFunctionPtrs(void)
 	pRtlAppendUnicodeStringToString = (void *)GetProcAddress(hntdll, "RtlAppendUnicodeStringToString");
 	pRtlAppendUnicodeToString = (void *)GetProcAddress(hntdll, "RtlAppendUnicodeToString");
 	pRtlCharToInteger = (void *)GetProcAddress(hntdll, "RtlCharToInteger");
+	pRtlCompareUnicodeString = (void *)GetProcAddress(hntdll, "RtlCompareUnicodeString");
+	pRtlCompareUnicodeStrings = (void *)GetProcAddress(hntdll, "RtlCompareUnicodeStrings");
 	pRtlCopyString = (void *)GetProcAddress(hntdll, "RtlCopyString");
 	pRtlCreateUnicodeString = (void *)GetProcAddress(hntdll, "RtlCreateUnicodeString");
 	pRtlCreateUnicodeStringFromAsciiz = (void *)GetProcAddress(hntdll, "RtlCreateUnicodeStringFromAsciiz");
@@ -1856,6 +1859,36 @@ static void test_RtlIsTextUnicode(void)
     HeapFree(GetProcessHeap(), 0, be_unicode_no_controls);
 }
 
+static void test_RtlCompareUnicodeString(void)
+{
+    WCHAR ch1, ch2;
+    UNICODE_STRING str1, str2;
+
+    str1.Buffer = &ch1;
+    str1.Length = str1.MaximumLength = sizeof(WCHAR);
+    str2.Buffer = &ch2;
+    str2.Length = str2.MaximumLength = sizeof(WCHAR);
+    for (ch1 = 0; ch1 < 512; ch1++)
+    {
+        for (ch2 = 0; ch2 < 1024; ch2++)
+        {
+            LONG res = pRtlCompareUnicodeString( &str1, &str2, FALSE );
+            ok( res == (ch1 - ch2), "wrong result %d %04x %04x\n", res, ch1, ch2 );
+            res = pRtlCompareUnicodeString( &str1, &str2, TRUE );
+            ok( res == (pRtlUpcaseUnicodeChar(ch1) - pRtlUpcaseUnicodeChar(ch2)),
+                "wrong result %d %04x %04x\n", res, ch1, ch2 );
+            if (pRtlCompareUnicodeStrings)
+            {
+                res = pRtlCompareUnicodeStrings( &ch1, 1, &ch2, 1, FALSE );
+                ok( res == (ch1 - ch2), "wrong result %d %04x %04x\n", res, ch1, ch2 );
+                res = pRtlCompareUnicodeStrings( &ch1, 1, &ch2, 1, TRUE );
+                ok( res == (pRtlUpcaseUnicodeChar(ch1) - pRtlUpcaseUnicodeChar(ch2)),
+                    "wrong result %d %04x %04x\n", res, ch1, ch2 );
+            }
+        }
+    }
+}
+
 static const WCHAR szGuid[] = { '{','0','1','0','2','0','3','0','4','-',
   '0','5','0','6','-'  ,'0','7','0','8','-','0','9','0','A','-',
   '0','B','0','C','0','D','0','E','0','F','0','A','}','\0' };
@@ -2522,6 +2555,7 @@ START_TEST(rtlstr)
     test_RtlGUIDFromString();
     test_RtlStringFromGUID();
     test_RtlIsTextUnicode();
+    test_RtlCompareUnicodeString();
     if(0)
     {
 	test_RtlUpcaseUnicodeChar();
diff --git a/include/winternl.h b/include/winternl.h
index 0e6cd4b8274..339d807fbdc 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -2386,6 +2386,7 @@ NTSYSAPI PDEBUG_BUFFER WINAPI RtlCreateQueryDebugBuffer(ULONG,BOOLEAN);
 NTSYSAPI ULONG     WINAPI RtlCompactHeap(HANDLE,ULONG);
 NTSYSAPI LONG      WINAPI RtlCompareString(const STRING*,const STRING*,BOOLEAN);
 NTSYSAPI LONG      WINAPI RtlCompareUnicodeString(const UNICODE_STRING*,const UNICODE_STRING*,BOOLEAN);
+NTSYSAPI LONG      WINAPI RtlCompareUnicodeStrings(const WCHAR*,SIZE_T,const WCHAR*,SIZE_T,BOOLEAN);
 NTSYSAPI NTSTATUS  WINAPI RtlCompressBuffer(USHORT,PUCHAR,ULONG,PUCHAR,ULONG,ULONG,PULONG,PVOID);
 NTSYSAPI DWORD     WINAPI RtlComputeCrc32(DWORD,const BYTE*,INT);
 NTSYSAPI NTSTATUS  WINAPI RtlConvertSidToUnicodeString(PUNICODE_STRING,PSID,BOOLEAN);