diff --git a/lib/curl_multibyte.c b/lib/curl_multibyte.c
index e78bb5002..e48334faf 100644
--- a/lib/curl_multibyte.c
+++ b/lib/curl_multibyte.c
@@ -64,13 +64,13 @@ char *Curl_convert_wchar_to_UTF8(const wchar_t *str_w)
   char *str_utf8 = NULL;
 
   if(str_w) {
-    int str_utf8_len = WideCharToMultiByte(CP_UTF8, 0, str_w, -1, NULL,
-                                           0, NULL, NULL);
-    if(str_utf8_len > 0) {
-      str_utf8 = malloc(str_utf8_len * sizeof(wchar_t));
+    int bytes = WideCharToMultiByte(CP_UTF8, 0, str_w, -1,
+                                    NULL, 0, NULL, NULL);
+    if(bytes > 0) {
+      str_utf8 = malloc(bytes);
       if(str_utf8) {
-        if(WideCharToMultiByte(CP_UTF8, 0, str_w, -1, str_utf8, str_utf8_len,
-                               NULL, FALSE) == 0) {
+        if(WideCharToMultiByte(CP_UTF8, 0, str_w, -1, str_utf8, bytes,
+                               NULL, NULL) == 0) {
           free(str_utf8);
           return NULL;
         }