diff --git a/encode.cc b/encode.cc
index d5cac3c..000f0bd 100644
--- a/encode.cc
+++ b/encode.cc
@@ -104,6 +104,8 @@ struct Encoder
 			tdom[i] /= std::sqrt(value(8*symbol_len));
 		for (int i = 0; i < guard_len; ++i) {
 			value x = value(i) / value(guard_len - 1);
+			value ratio(0.5);
+			x = std::min(x, ratio) / ratio;
 			x = value(0.5) * (value(1) - std::cos(DSP::Const<value>::Pi() * x));
 			guard[i] = DSP::lerp(guard[i], tdom[i+symbol_len-guard_len], x);
 		}