diff --git a/decode.cc b/decode.cc
index c578ac8..99a1494 100644
--- a/decode.cc
+++ b/decode.cc
@@ -226,8 +226,14 @@ struct Decoder : Common
 					demod[i] *= DSP::polar<value>(1, -tse(i+tone_off));
 				for (int i = 0; i < tone_count; ++i)
 					chan[i] *= DSP::polar<value>(1, tse(i+tone_off));
-				for (int i = pilot_off; i < tone_count; i += block_length)
-					chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
+				if (differential) {
+					for (int i = 0; i < tone_count; ++i)
+						if (i % block_length != reserved_off)
+							chan[i] = fdom[bin(i+tone_off)];
+				} else {
+					for (int i = pilot_off; i < tone_count; i += block_length)
+						chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
+				}
 				value sp = 0, np = 0;
 				for (int i = 0; i < pilot_tones; ++i) {
 					cmplx hard(1, 0);
diff --git a/encode.cc b/encode.cc
index 85de1be..e24b339 100644
--- a/encode.cc
+++ b/encode.cc
@@ -37,6 +37,7 @@ struct Encoder : public Common
 	cmplx kern[symbol_len];
 	cmplx guard[guard_len];
 	cmplx tone[tone_count];
+	cmplx prev[tone_count];
 	value weight[guard_len];
 	value papr_min, papr_max;
 
@@ -93,6 +94,11 @@ struct Encoder : public Common
 	}
 	void symbol(bool papr_reduction = true, bool guard_interval = true)
 	{
+		for (int i = 0; differential && i < tone_count; ++i)
+			if (!papr_reduction)
+				prev[i] = 1;
+			else if (i % block_length != reserved_off)
+				prev[i] = tone[i] *= prev[i];
 		for (int i = 0; i < symbol_len; ++i)
 			fdom[i] = 0;
 		for (int i = 0; i < tone_count; ++i)