static long curl_low_speed_limit = -1;
 static long curl_low_speed_time = -1;
 static int curl_ftp_no_epsv = 0;
-static char *curl_http_proxy = NULL;
+static const char *curl_http_proxy = NULL;
 
 static struct curl_slist *pragma_header;
 
                return 0;
        }
        if (!strcmp("http.proxy", var)) {
-               if (curl_http_proxy == NULL) {
-                       if (!value)
-                               return config_error_nonbool(var);
-                       curl_http_proxy = xstrdup(value);
-               }
+               if (curl_http_proxy == NULL)
+                       return git_config_string(&curl_http_proxy, var, value);
                return 0;
        }
 
        pragma_header = NULL;
 
        if (curl_http_proxy) {
-               free(curl_http_proxy);
+               free((void *)curl_http_proxy);
                curl_http_proxy = NULL;
        }
 }