diff --git a/lib/decoding/tch_f_decoder_impl.cc b/lib/decoding/tch_f_decoder_impl.cc
index 75d2402..5601c00 100644
--- a/lib/decoding/tch_f_decoder_impl.cc
+++ b/lib/decoding/tch_f_decoder_impl.cc
@@ -57,6 +57,11 @@
             throw std::runtime_error("TCH/F Decoder: can't open file\n");
         }
 
+        if (d_tch_mode == MODE_SPEECH_EFR)
+        {
+            fwrite(amr_nb_magic, 1, 6, d_speech_file);
+        }
+
         int j, k, B;
         for (k = 0; k < CONV_SIZE; k++)
         {
diff --git a/lib/decoding/tch_f_decoder_impl.h b/lib/decoding/tch_f_decoder_impl.h
index 7caa30f..aa443b7 100644
--- a/lib/decoding/tch_f_decoder_impl.h
+++ b/lib/decoding/tch_f_decoder_impl.h
@@ -53,6 +53,7 @@
                 FILE * d_speech_file;
                 enum tch_mode d_tch_mode;
                 void decode(pmt::pmt_t msg);
+                const unsigned char amr_nb_magic[6] = { 0x23, 0x21, 0x41, 0x4d, 0x52, 0x0a };
             public:
                 tch_f_decoder_impl(tch_mode mode, const std::string &file);
                 ~tch_f_decoder_impl();