diff --git a/src/decoder/DecoderControl.cxx b/src/decoder/DecoderControl.cxx
index 648e816d8..c41165d1e 100644
--- a/src/decoder/DecoderControl.cxx
+++ b/src/decoder/DecoderControl.cxx
@@ -108,12 +108,13 @@ bool
 DecoderControl::Seek(SongTime t)
 {
 	assert(state != DecoderState::START);
+	assert(state != DecoderState::ERROR);
 
 	switch (state) {
 	case DecoderState::START:
+	case DecoderState::ERROR:
 		gcc_unreachable();
 
-	case DecoderState::ERROR:
 	case DecoderState::STOP:
 		return false;