diff --git a/dlls/shlwapi/url.c b/dlls/shlwapi/url.c
index ae2f408320a..bb5e633c237 100644
--- a/dlls/shlwapi/url.c
+++ b/dlls/shlwapi/url.c
@@ -42,6 +42,21 @@ HRESULT WINAPI MLBuildResURLW(LPCWSTR,HMODULE,DWORD,LPCWSTR,LPWSTR,DWORD);
 
 WINE_DEFAULT_DEBUG_CHANNEL(shell);
 
+static inline WCHAR *heap_strdupAtoW(const char *str)
+{
+    LPWSTR ret = NULL;
+
+    if(str) {
+        DWORD len;
+
+        len = MultiByteToWideChar(CP_ACP, 0, str, -1, NULL, 0);
+        ret = HeapAlloc(GetProcessHeap(), 0, len*sizeof(WCHAR));
+        MultiByteToWideChar(CP_ACP, 0, str, -1, ret, len);
+    }
+
+    return ret;
+}
+
 /* The following schemes were identified in the native version of
  * SHLWAPI.DLL version 5.50
  */
@@ -234,7 +249,6 @@ HRESULT WINAPI UrlCanonicalizeA(LPCSTR pszUrl, LPSTR pszCanonicalized,
 {
     LPWSTR url, canonical;
     HRESULT ret;
-    DWORD   len;
 
     TRACE("(%s, %p, %p, 0x%08x) *pcchCanonicalized: %d\n", debugstr_a(pszUrl), pszCanonicalized,
         pcchCanonicalized, dwFlags, pcchCanonicalized ? *pcchCanonicalized : -1);
@@ -242,8 +256,7 @@ HRESULT WINAPI UrlCanonicalizeA(LPCSTR pszUrl, LPSTR pszCanonicalized,
     if(!pszUrl || !pszCanonicalized || !pcchCanonicalized || !*pcchCanonicalized)
 	return E_INVALIDARG;
 
-    len = strlen(pszUrl)+1;
-    url = HeapAlloc(GetProcessHeap(), 0, len*sizeof(WCHAR));
+    url = heap_strdupAtoW(pszUrl);
     canonical = HeapAlloc(GetProcessHeap(), 0, *pcchCanonicalized*sizeof(WCHAR));
     if(!url || !canonical) {
         HeapFree(GetProcessHeap(), 0, url);
@@ -251,13 +264,12 @@ HRESULT WINAPI UrlCanonicalizeA(LPCSTR pszUrl, LPSTR pszCanonicalized,
         return E_OUTOFMEMORY;
     }
 
-    MultiByteToWideChar(0, 0, pszUrl, -1, url, len);
-
     ret = UrlCanonicalizeW(url, canonical, pcchCanonicalized, dwFlags);
     if(ret == S_OK)
         WideCharToMultiByte(0, 0, canonical, -1, pszCanonicalized,
                 *pcchCanonicalized+1, 0, 0);
 
+    HeapFree(GetProcessHeap(), 0, url);
     HeapFree(GetProcessHeap(), 0, canonical);
     return ret;
 }