diff --git a/fluid/DeepASR/decoder/post_decode_faster.cc b/fluid/DeepASR/decoder/post_decode_faster.cc
index 6b318000e380793c2042110f51ae2551d85ebd0b..d7f1d1ab34a18285d1d96b9ff6a67cff42d519b3 100644
--- a/fluid/DeepASR/decoder/post_decode_faster.cc
+++ b/fluid/DeepASR/decoder/post_decode_faster.cc
@@ -1,4 +1,4 @@
-/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -69,7 +69,8 @@ Decoder::~Decoder() {
 }
 
 std::string Decoder::decode(
-    std::string key, std::vector<std::vector<kaldi::BaseFloat>>& log_probs) {
+    std::string key,
+    const std::vector<std::vector<kaldi::BaseFloat>>& log_probs) {
   size_t num_frames = log_probs.size();
   size_t dim_label = log_probs[0].size();
 
diff --git a/fluid/DeepASR/decoder/post_decode_faster.h b/fluid/DeepASR/decoder/post_decode_faster.h
index c0b54cdf9fcb6603f34904b0fd7ee906bd20f12d..2e31a1c19e40bd879a1c76f1542b94eaa853be12 100644
--- a/fluid/DeepASR/decoder/post_decode_faster.h
+++ b/fluid/DeepASR/decoder/post_decode_faster.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -37,8 +37,9 @@ public:
   std::vector<std::string> decode(std::string posterior_rspecifier);
 
   // Accept the scores of one utterance and return the decoding result
-  std::string decode(std::string key,
-                     std::vector<std::vector<kaldi::BaseFloat>> &log_probs);
+  std::string decode(
+      std::string key,
+      const std::vector<std::vector<kaldi::BaseFloat>> &log_probs);
 
 private:
   // For decoding one utterance
diff --git a/fluid/DeepASR/decoder/pybind.cc b/fluid/DeepASR/decoder/pybind.cc
index 1b91f02b89ffd259f7a24a005ec96bd780287e25..56439d180263b4d753eccd82826d1b39c9d2fa85 100644
--- a/fluid/DeepASR/decoder/pybind.cc
+++ b/fluid/DeepASR/decoder/pybind.cc
@@ -1,4 +1,4 @@
-/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -27,12 +27,13 @@ PYBIND11_MODULE(post_decode_faster, m) {
       .def("decode",
            (std::vector<std::string> (Decoder::*)(std::string)) &
                Decoder::decode,
-           "Decode one input probability matrix "
-           "and return the transcription")
-      .def("decode",
-           (std::string (Decoder::*)(
-               std::string, std::vector<std::vector<kaldi::BaseFloat>>&)) &
-               Decoder::decode,
-           "Decode one input probability matrix "
-           "and return the transcription");
+           "Decode for the probability matrices in specifier "
+           "and return the transcriptions.")
+      .def(
+          "decode",
+          (std::string (Decoder::*)(
+              std::string, const std::vector<std::vector<kaldi::BaseFloat>>&)) &
+              Decoder::decode,
+          "Decode one input probability matrix "
+          "and return the transcription.");
 }
diff --git a/fluid/DeepASR/decoder/setup.py b/fluid/DeepASR/decoder/setup.py
index 1818ecbf003000285e190ac21095e435e8bfb0ad..a98c0b4cc17717a6769b8322e4f5afe3de6ab2de 100644
--- a/fluid/DeepASR/decoder/setup.py
+++ b/fluid/DeepASR/decoder/setup.py
@@ -1,4 +1,4 @@
-#  Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+#  Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.