diff --git a/common.hh b/common.hh
index e64f26c..7a1eb4f 100644
--- a/common.hh
+++ b/common.hh
@@ -36,6 +36,7 @@ struct Common
 	int data_bits;
 	int data_bytes;
 	int code_order;
+	int oper_mode;
 	int tone_off;
 	int pilot_off;
 	int reserved_off;
@@ -44,9 +45,9 @@ struct Common
 
 	Common() : crc0(0x8F6E37A0) {}
 
-	void setup(int oper_mode)
+	void setup(int mode)
 	{
-		switch (oper_mode) {
+		switch (mode) {
 		case 0:
 			mod_bits = 1;
 			symbol_count = 8;
@@ -274,6 +275,7 @@ struct Common
 		default:
 			return;
 		}
+		oper_mode = mode;
 		data_bytes = data_bits / 8;
 	}
 };
diff --git a/decode.cc b/decode.cc
index 559b06c..f84fa5d 100644
--- a/decode.cc
+++ b/decode.cc
@@ -234,11 +234,12 @@ struct Decoder : Common
 			auto clamp = [](int v){ return v < -127 ? -127 : v > 127 ? 127 : v; };
 			for (int i = 0; i < pilot_tones; ++i)
 				meta[i] = clamp(std::nearbyint(127 * demod_or_erase(fdom[bin(i*block_length+first_pilot+tone_off)], chan[i*block_length+first_pilot]).real() * nrz(seq1())));
-			int oper_mode = hadamard_decoder(meta);
-			if (oper_mode < 0 || oper_mode > 27) {
-				std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl;
+			int mode = hadamard_decoder(meta);
+			if (mode < 0 || mode > 27) {
+				std::cerr << "operation mode " << mode << " unsupported." << std::endl;
 				continue;
 			}
+			oper_mode = mode;
 			std::cerr << "oper mode: " << oper_mode << std::endl;
 			if (oper_mode >= 10) {
 				for (int i = 0; i < tone_count; ++i)