diff --git a/README.md b/README.md
index 592e033..3db1a69 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,13 @@
 
 Quick start:
 
-Encode file ```uncoded.dat``` with ```64800``` bits to ```encoded.wav``` [WAV](https://en.wikipedia.org/wiki/WAV) audio file with 8000 Hz sample rate, 16 bits and only 1 (real) channel:
+Create file ```uncoded.dat``` with ```64768``` bits of random data:
+
+```
+dd if=/dev/urandom of=uncoded.dat bs=1 count=8096
+```
+
+Encode file ```uncoded.dat``` to ```encoded.wav``` [WAV](https://en.wikipedia.org/wiki/WAV) audio file with 8000 Hz sample rate, 16 bits and only 1 (real) channel:
 
 ```
 ./encode encoded.wav 8000 16 1 uncoded.dat
diff --git a/decode.cc b/decode.cc
index 7011dac..7786ef1 100644
--- a/decode.cc
+++ b/decode.cc
@@ -174,7 +174,8 @@ struct Decoder
 	DSP::Resampler<value, filter_len, 3> resample;
 	DSP::BipBuffer<cmplx, buffer_len> input_hist;
 	SchmidlCox<value, cmplx, search_pos, symbol_len/2, guard_len> correlator;
-	CODE::CRC<uint16_t> crc;
+	CODE::CRC<uint16_t> crc0;
+	CODE::CRC<uint32_t> crc1;
 	CODE::OrderedStatisticsDecoder<255, 71, 4> osddec;
 	int8_t genmat[255*71];
 	cmplx head[symbol_len], tail[symbol_len];
@@ -232,7 +233,7 @@ struct Decoder
 		return sum / (count * symbol_len/2);
 	}
 	Decoder(uint8_t *out, DSP::ReadPCM<value> *pcm, int skip_count) :
-		pcm(pcm), resample(rate, (rate * 19) / 40, 2), correlator(mls0_seq()), crc(0xA8F4)
+		pcm(pcm), resample(rate, (rate * 19) / 40, 2), correlator(mls0_seq()), crc0(0xA8F4), crc1(0xD419CC15)
 	{
 		CODE::BoseChaudhuriHocquenghemGenerator<255, 71>::matrix(genmat, true, {
 			0b100011101, 0b101110111, 0b111110011, 0b101101001,
@@ -287,9 +288,9 @@ struct Decoder
 		uint16_t cs = 0;
 		for (int i = 0; i < 16; ++i)
 			cs |= (uint16_t)CODE::get_be_bit(data, i+55) << i;
-		crc.reset();
-		if (crc(md<<9) != cs) {
-			std::cerr << "CRC error." << std::endl;
+		crc0.reset();
+		if (crc0(md<<9) != cs) {
+			std::cerr << "header CRC error." << std::endl;
 			return;
 		}
 		if ((md&255) != 2) {
@@ -339,6 +340,11 @@ struct Decoder
 				}
 			}
 		}
+		crc1.reset();
+		for (int i = 0; i < data_bits / 8; ++i)
+			crc1(out[i]);
+		if (crc1())
+			std::cerr << "payload CRC error." << std::endl;
 	}
 };
 
@@ -366,8 +372,8 @@ int main(int argc, char **argv)
 	if (argc > 3)
 		skip_count = std::atoi(argv[3]);
 
-	const int length = 64800 / 8;
-	uint8_t *output_data = new uint8_t[length];
+	const int code_len = 64800 / 8;
+	uint8_t *output_data = new uint8_t[code_len];
 
 	switch (input_file.rate()) {
 	case 8000:
@@ -392,7 +398,8 @@ int main(int argc, char **argv)
 		std::cerr << "Couldn't open file \"" << output_name << "\" for writing." << std::endl;
 		return 1;
 	}
-	for (int i = 0; i < length; ++i)
+	const int data_len = code_len - 32 / 8;
+	for (int i = 0; i < data_len; ++i)
 		output_file.put(output_data[i]);
 	delete []output_data;
 	return 0;
diff --git a/encode.cc b/encode.cc
index 188dfb1..46b82b6 100644
--- a/encode.cc
+++ b/encode.cc
@@ -36,7 +36,8 @@ struct Encoder
 	static const int mls2_poly = 0b100101010001;
 	DSP::WritePCM<value> *pcm;
 	DSP::FastFourierTransform<symbol_len, cmplx, 1> bwd;
-	CODE::CRC<uint16_t> crc;
+	CODE::CRC<uint16_t> crc0;
+	CODE::CRC<uint32_t> crc1;
 	CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc;
 	cmplx fdom[symbol_len];
 	cmplx tdom[symbol_len];
@@ -109,8 +110,8 @@ struct Encoder
 		uint8_t data[9] = { 0 }, parity[23] = { 0 };
 		for (int i = 0; i < 55; ++i)
 			CODE::set_be_bit(data, i, (md>>i)&1);
-		crc.reset();
-		uint16_t cs = crc(md << 9);
+		crc0.reset();
+		uint16_t cs = crc0(md << 9);
 		for (int i = 0; i < 16; ++i)
 			CODE::set_be_bit(data, i+55, (cs>>i)&1);
 		bchenc(data, parity);
@@ -130,7 +131,7 @@ struct Encoder
 		symbol();
 	}
 	Encoder(DSP::WritePCM<value> *pcm, uint8_t *inp, int freq_off, uint64_t call_sign) :
-		pcm(pcm), crc(0xA8F4), bchenc({
+		pcm(pcm), crc0(0xA8F4), crc1(0xD419CC15), bchenc({
 			0b100011101, 0b101110111, 0b111110011, 0b101101001,
 			0b110111101, 0b111100111, 0b100101011, 0b111010111,
 			0b000010011, 0b101100101, 0b110001011, 0b101100011,
@@ -146,6 +147,11 @@ struct Encoder
 		schmidl_cox();
 		meta_data((call_sign << 8) | 2);
 		pilot_block();
+		crc1.reset();
+		for (int i = 0; i < (data_bits-32)/8; ++i)
+			crc1(inp[i]);
+		for (int i = 0; i < 4; ++i)
+			inp[(data_bits-32)/8+i] = (crc1() >> (8*i)) & 255;
 		for (int j = 0; j < data_rows; ++j) {
 			for (int i = 0; i < data_cols; ++i) {
 				value tmp[Mod::BITS];
@@ -225,9 +231,10 @@ int main(int argc, char **argv)
 		std::cerr << "Couldn't open file \"" << input_name << "\" for reading." << std::endl;
 		return 1;
 	}
-	const int length = 64800 / 8;
-	uint8_t *input_data = new uint8_t[length];
-	for (int i = 0; i < length; ++i)
+	const int code_len = 64800 / 8;
+	const int data_len = code_len - 32 / 8;
+	uint8_t *input_data = new uint8_t[code_len];
+	for (int i = 0; i < data_len; ++i)
 		input_data[i] = input_file.get();
 
 	DSP::WriteWAV<value> output_file(output_name, output_rate, output_bits, output_chan);