diff --git a/reactos/dll/win32/shlwapi/shlwapi.spec b/reactos/dll/win32/shlwapi/shlwapi.spec
index b7ea3aa6fff..b6426e784db 100644
--- a/reactos/dll/win32/shlwapi/shlwapi.spec
+++ b/reactos/dll/win32/shlwapi/shlwapi.spec
@@ -215,7 +215,7 @@
 215 stdcall -noname SHAnsiToUnicode(str ptr long)
 216 stdcall -noname SHAnsiToUnicodeCP(long str ptr long)
 217 stdcall -noname SHUnicodeToAnsi(wstr ptr ptr)
-218 stdcall -noname SHUnicodeToAnsiCP(long wstr ptr ptr)
+218 stdcall -noname SHUnicodeToAnsiCP(long wstr ptr long)
 219 stdcall -noname QISearch(long long long long)
 220 stdcall -noname SHSetDefaultDialogFont(ptr long)
 221 stdcall -noname SHRemoveDefaultDialogFont(ptr)
@@ -477,7 +477,7 @@
 477 stub -noname SHCreatePropertyBagOnMemory
 478 stdcall -noname IUnknown_TranslateAcceleratorIO(ptr ptr)
 479 stub -noname IUnknown_UIActivateIO
-480 stub -noname UrlCrackW
+480 stdcall -noname UrlCrackW(wstr long long ptr) wininet.InternetCrackUrlW
 481 stdcall -noname IUnknown_HasFocusIO(ptr)
 482 stub -noname SHMessageBoxHelpA
 483 stub -noname SHMessageBoxHelpW
diff --git a/reactos/dll/win32/shlwapi/string.c b/reactos/dll/win32/shlwapi/string.c
index da0dee3cfd2..755360d790a 100644
--- a/reactos/dll/win32/shlwapi/string.c
+++ b/reactos/dll/win32/shlwapi/string.c
@@ -2477,20 +2477,24 @@ DWORD WINAPI SHAnsiToUnicode(LPCSTR lpSrcStr, LPWSTR lpDstStr, int iLen)
  *  CodePage [I] Code page to use for the conversion
  *  lpSrcStr [I] Source Unicode string to convert
  *  lpDstStr [O] Destination for converted Ascii string
- *  lpiLen   [I/O] Input length of lpDstStr/destination for length of lpDstStr
+ *  dstlen   [I] Length of buffer at lpDstStr
  *
  * RETURNS
- *  Success: The number of characters that result from the conversion.
- *  Failure: 0.
+ *  Success: The length in bytes of the result at lpDstStr (including the terminator)
+ *  Failure: When using CP_UTF8, CP_UTF7 or 0xc350 as codePage, 0 is returned and
+ *           the result is not nul-terminated.
+ *           When using a different codepage, the length in bytes of the truncated
+ *           result at lpDstStr (including the terminator) is returned and
+ *           lpDstStr is always nul-terminated.
+ *
  */
-INT WINAPI SHUnicodeToAnsiCP(UINT CodePage, LPCWSTR lpSrcStr, LPSTR lpDstStr,
-                             LPINT lpiLen)
+DWORD WINAPI SHUnicodeToAnsiCP(UINT CodePage, LPCWSTR lpSrcStr, LPSTR lpDstStr, int dstlen)
 {
   static const WCHAR emptyW[] = { '\0' };
   int len , reqLen;
   LPSTR mem;
 
-  if (!lpDstStr || !lpiLen)
+  if (!lpDstStr || !dstlen)
     return 0;
 
   if (!lpSrcStr)
@@ -2509,41 +2513,41 @@ INT WINAPI SHUnicodeToAnsiCP(UINT CodePage, LPCWSTR lpSrcStr, LPSTR lpDstStr,
   case CP_UTF8:
     {
       DWORD dwMode = 0;
-      INT nWideCharCount = len - 1;
+      INT lenW = len - 1;
+      INT needed = dstlen - 1;
+      HRESULT hr;
 
-      if (ConvertINetUnicodeToMultiByte(&dwMode, CodePage, lpSrcStr,
-                                        &nWideCharCount, lpDstStr,
-                                        lpiLen) == S_OK)
+      /* try the user supplied buffer first */
+      hr = ConvertINetUnicodeToMultiByte(&dwMode, CodePage, lpSrcStr, &lenW, lpDstStr, &needed);
+      if (hr == S_OK)
+      {
+        lpDstStr[needed] = '\0';
+        return needed + 1;
+      }
+
+      /* user buffer too small. exclude termination and copy as much as possible */
+      lenW = len;
+      hr = ConvertINetUnicodeToMultiByte(&dwMode, CodePage, lpSrcStr, &lenW, NULL, &needed);
+      needed++;
+      mem = HeapAlloc(GetProcessHeap(), 0, needed);
+      if (!mem)
         return 0;
 
-      if (nWideCharCount < len - 1)
+      hr = ConvertINetUnicodeToMultiByte(&dwMode, CodePage, lpSrcStr, &len, mem, &needed);
+      if (hr == S_OK)
       {
-        mem = HeapAlloc(GetProcessHeap(), 0, *lpiLen);
-        if (!mem)
-          return 0;
-
-        *lpiLen = 0;
-
-        if (ConvertINetUnicodeToMultiByte(&dwMode, CodePage, lpSrcStr, &len,
-                                          mem, lpiLen) != S_OK)
-        {
-          SHTruncateString(mem, *lpiLen);
-          lstrcpynA(lpDstStr, mem, *lpiLen + 1);
-          HeapFree(GetProcessHeap(), 0, mem);
-          return *lpiLen + 1;
-        }
-        HeapFree(GetProcessHeap(), 0, mem);
-        return *lpiLen;
+          reqLen = SHTruncateString(mem, dstlen);
+          if (reqLen > 0) memcpy(lpDstStr, mem, reqLen-1);
       }
-      lpDstStr[*lpiLen] = '\0';
-      return *lpiLen;
+      HeapFree(GetProcessHeap(), 0, mem);
+      return 0;
     }
   default:
     break;
   }
 
-  reqLen = WideCharToMultiByte(CodePage, 0, lpSrcStr, len, lpDstStr,
-                               *lpiLen, NULL, NULL);
+  /* try the user supplied buffer first */
+  reqLen = WideCharToMultiByte(CodePage, 0, lpSrcStr, len, lpDstStr, dstlen, NULL, NULL);
 
   if (!reqLen && GetLastError() == ERROR_INSUFFICIENT_BUFFER)
   {
@@ -2556,12 +2560,12 @@ INT WINAPI SHUnicodeToAnsiCP(UINT CodePage, LPCWSTR lpSrcStr, LPSTR lpDstStr,
         reqLen = WideCharToMultiByte(CodePage, 0, lpSrcStr, len, mem,
                                      reqLen, NULL, NULL);
 
-        reqLen = SHTruncateString(mem, *lpiLen);
+        reqLen = SHTruncateString(mem, dstlen -1);
         reqLen++;
 
-        lstrcpynA(lpDstStr, mem, *lpiLen);
-
+        lstrcpynA(lpDstStr, mem, reqLen);
         HeapFree(GetProcessHeap(), 0, mem);
+        lpDstStr[reqLen-1] = '\0';
       }
     }
   }
@@ -2586,9 +2590,7 @@ INT WINAPI SHUnicodeToAnsiCP(UINT CodePage, LPCWSTR lpSrcStr, LPSTR lpDstStr,
  */
 INT WINAPI SHUnicodeToAnsi(LPCWSTR lpSrcStr, LPSTR lpDstStr, INT iLen)
 {
-    INT myint = iLen;
-
-    return SHUnicodeToAnsiCP(CP_ACP, lpSrcStr, lpDstStr, &myint);
+    return SHUnicodeToAnsiCP(CP_ACP, lpSrcStr, lpDstStr, iLen);
 }
 
 /*************************************************************************