diff --git a/src/oss_util.rs b/src/oss_util.rs
index d42ea5e..748b9a9 100644
--- a/src/oss_util.rs
+++ b/src/oss_util.rs
@@ -86,14 +86,14 @@ impl OSSClient {
         let expire_secs = current_secs + expire_in_seconds;
     
         signed_url.push_str("?Expires=");
-        signed_url.push_str(expire_secs.to_string().as_str());
+        signed_url.push_str(&expire_secs.to_string());
         signed_url.push_str("&OSSAccessKeyId=");
         signed_url.push_str(&urlencoding::encode(&self.access_key_id));
         signed_url.push_str("&Signature=");
     
         let to_be_signed = get_to_be_signed(verb, expire_secs, bucket_name, key);
         let signature = calc_hmac_sha1(self.access_key_secret.as_bytes(), to_be_signed.as_bytes());
-        signed_url.push_str(&urlencoding::encode(signature.as_str()));
+        signed_url.push_str(&urlencoding::encode(&signature));
     
         signed_url
     }
@@ -116,7 +116,7 @@ fn get_to_be_signed(verb: &str, expire_secs: u64, bucket_name: &str, key: &str)
     to_be_signed.push_str("\n");
     to_be_signed.push_str("\n");
     to_be_signed.push_str("\n");
-    to_be_signed.push_str(expire_secs.to_string().as_str());
+    to_be_signed.push_str(&expire_secs.to_string());
     to_be_signed.push_str("\n");
     to_be_signed.push_str("/");
     to_be_signed.push_str(bucket_name);