diff --git a/dlls/mlang/mlang.c b/dlls/mlang/mlang.c
index a60ad70..8a66a19 100644
--- a/dlls/mlang/mlang.c
+++ b/dlls/mlang/mlang.c
@@ -2236,6 +2236,7 @@ static HRESULT WINAPI fnIMultiLanguage2_GetRfc1766FromLcid(
 
     TRACE("%p %04x %p\n", iface, lcid, pbstrRfc1766);
 
+    ZeroMemory(buf, MAX_RFC1766_NAME * sizeof(WCHAR));
     if (lcid_to_rfc1766W( lcid, buf, MAX_RFC1766_NAME ))
     {
         *pbstrRfc1766 = SysAllocString( buf );
diff --git a/dlls/mlang/tests/Makefile.in b/dlls/mlang/tests/Makefile.in
index 0df1440..a6da644 100644
--- a/dlls/mlang/tests/Makefile.in
+++ b/dlls/mlang/tests/Makefile.in
@@ -3,7 +3,7 @@ TOPOBJDIR = ../../..
 SRCDIR    = @srcdir@
 VPATH     = @srcdir@
 TESTDLL   = mlang.dll
-IMPORTS   = uuid ole32 gdi32 kernel32
+IMPORTS   = uuid ole32 oleaut32 gdi32 kernel32
 
 CTESTS = \
 	mlang.c
diff --git a/dlls/mlang/tests/mlang.c b/dlls/mlang/tests/mlang.c
index c036f7a..657e8a0 100644
--- a/dlls/mlang/tests/mlang.c
+++ b/dlls/mlang/tests/mlang.c
@@ -255,6 +255,32 @@ static const char *dump_mime_flags(DWORD flags)
 }
 #endif
 
+static BOOL check_convertible(IMultiLanguage2 *iML2, UINT from, UINT to)
+{
+    CHAR convert[MAX_PATH];
+    BYTE dest[MAX_PATH];
+    HRESULT hr;
+    UINT srcsz, destsz;
+
+    static WCHAR strW[] = {'a','b','c',0};
+
+    srcsz = -1;
+    destsz = MAX_PATH;
+    hr = IMultiLanguage2_ConvertStringFromUnicode(iML2, NULL, from, strW,
+                                                  &srcsz, convert, &destsz);
+    if (hr != S_OK)
+        return FALSE;
+
+    srcsz = -1;
+    destsz = MAX_PATH;
+    hr = IMultiLanguage2_ConvertString(iML2, NULL, from, to, (BYTE *)convert,
+                                       &srcsz, dest, &destsz);
+    if (hr != S_OK)
+        return FALSE;
+
+    return TRUE;
+}
+
 static void test_EnumCodePages(IMultiLanguage2 *iML2, DWORD flags)
 {
     IEnumCodePage *iEnumCP = NULL;
@@ -316,6 +342,8 @@ static void test_EnumCodePages(IMultiLanguage2 *iML2, DWORD flags)
 	CPINFOEXA cpinfoex;
 	CHARSETINFO csi;
 	MIMECSETINFO mcsi;
+        BOOL convertible;
+        HRESULT check = S_OK;
 	static const WCHAR autoW[] = {'_','a','u','t','o',0};
 
 #ifdef DUMP_CP_INFO
@@ -376,12 +404,16 @@ static void test_EnumCodePages(IMultiLanguage2 *iML2, DWORD flags)
 	    ret = IMultiLanguage2_IsConvertible(iML2, CP_UNICODE, cpinfo[i].uiCodePage);
 	    ok(ret == S_OK, "IMultiLanguage2_IsConvertible(CP_UNICODE -> %u) = %08x\n", cpinfo[i].uiCodePage, ret);
 
+            convertible = check_convertible(iML2, cpinfo[i].uiCodePage, CP_UTF8);
+            if (!convertible)
+                check = S_FALSE;
+
 	    TRACE_2("Call IMultiLanguage2_IsConvertible\n");
 	    ret = IMultiLanguage2_IsConvertible(iML2, cpinfo[i].uiCodePage, CP_UTF8);
-	    ok(ret == S_OK, "IMultiLanguage2_IsConvertible(%u -> CP_UTF8) = %08x\n", cpinfo[i].uiCodePage, ret);
+	    ok(ret == check, "IMultiLanguage2_IsConvertible(%u -> CP_UTF8) = %08x\n", cpinfo[i].uiCodePage, ret);
 	    TRACE_2("Call IMultiLanguage2_IsConvertible\n");
 	    ret = IMultiLanguage2_IsConvertible(iML2, CP_UTF8, cpinfo[i].uiCodePage);
-	    ok(ret == S_OK, "IMultiLanguage2_IsConvertible(CP_UTF8 -> %u) = %08x\n", cpinfo[i].uiCodePage, ret);
+	    ok(ret == check, "IMultiLanguage2_IsConvertible(CP_UTF8 -> %u) = %08x\n", cpinfo[i].uiCodePage, ret);
 	}
 	else
 	    trace("IsValidCodePage failed for cp %u\n", cpinfo[i].uiCodePage);
@@ -654,12 +686,37 @@ static void IMLangFontLink_Test(IMLangFontLink* iMLFL)
     ok(CodePage == 1252, "Incorrect CodePage Returned (%i)\n",CodePage);
 }
 
+/* copied from libs/wine/string.c */
+WCHAR *strstrW(const WCHAR *str, const WCHAR *sub)
+{
+    while (*str)
+    {
+        const WCHAR *p1 = str, *p2 = sub;
+        while (*p1 && *p2 && *p1 == *p2) { p1++; p2++; }
+        if (!*p2) return (WCHAR *)str;
+        str++;
+    }
+    return NULL;
+}
+
+static CHAR string1[MAX_PATH], string2[MAX_PATH];
+
+#define ok_w2(format, szString1, szString2) \
+\
+    if (lstrcmpW(szString1, szString2) != 0) \
+    { \
+        WideCharToMultiByte(CP_ACP, 0, szString1, -1, string1, MAX_PATH, NULL, NULL); \
+        WideCharToMultiByte(CP_ACP, 0, szString2, -1, string2, MAX_PATH, NULL, NULL); \
+        ok(0, format, string1, string2); \
+    }
+
 static void test_rfc1766(IMultiLanguage2 *iML2)
 {
     IEnumRfc1766 *pEnumRfc1766;
     RFC1766INFO info;
     ULONG n;
     HRESULT ret;
+    BSTR rfcstr;
 
     ret = IMultiLanguage2_EnumRfc1766(iML2, LANG_NEUTRAL, &pEnumRfc1766);
     ok(ret == S_OK, "IMultiLanguage2_EnumRfc1766 error %08x\n", ret);
@@ -675,7 +732,18 @@ static void test_rfc1766(IMultiLanguage2 *iML2)
 #endif
 
         ok(n == 1, "couldn't fetch 1 RFC1766INFO structure\n");
-        ok(IsValidLocale(info.lcid, LCID_SUPPORTED), "invalid lcid %04x\n", info.lcid);
+
+        /* verify the Rfc1766 value */
+        ret = IMultiLanguage2_GetRfc1766FromLcid(iML2, info.lcid, &rfcstr);
+        ok(ret == S_OK, "Expected S_OK, got %08x\n", ret);
+        ok_w2("%s %s\n", info.wszRfc1766, rfcstr);
+
+        /* not an exact 1:1 correspondence between lcid and rfc1766 in the
+         * mlang database, e.g., nb-no -> 1044 -> no */
+        ok(strstrW(info.wszRfc1766, rfcstr) != NULL,
+           "Expected matching locale names\n");
+
+        SysFreeString(rfcstr);
     }
     IEnumRfc1766_Release(pEnumRfc1766);
 }
-- 
1.5.4.3