diff --git a/src/manta/uart/cobs_decode.py b/src/manta/uart/cobs_decode.py
index f7268c0..5b57dc0 100644
--- a/src/manta/uart/cobs_decode.py
+++ b/src/manta/uart/cobs_decode.py
@@ -69,7 +69,7 @@ class COBSDecode(wiring.Component):
 
         m.d.comb += [
             self.source.data.eq(fifo.r_data),
-            self.source.valid.eq(fifo.r_rdy),
+            self.source.valid.eq(fifo.r_rdy & (fsm.ongoing("IDLE") | (fifo.r_level > 1))),
             self.source.last.eq(fsm.ongoing("IDLE") & self.source.valid & (fifo.r_level == 1)),
             fifo.r_en.eq(self.source.valid & self.source.ready),
         ]
diff --git a/test/test_cobs_decode.py b/test/test_cobs_decode.py
index 815d44b..1497bf4 100644
--- a/test/test_cobs_decode.py
+++ b/test/test_cobs_decode.py
@@ -36,7 +36,7 @@ async def test_cobs_decode_static(ctx):
     ]
 
     for data in testcases:
-        await decode_and_compare(ctx, data, tx_irritate=False, rx_irritate=False)
+        await decode_and_compare(ctx, data, tx_irritate=True, rx_irritate=True)
 
 
 async def decode(ctx, data, tx_irritate, rx_irritate):
@@ -54,11 +54,11 @@ async def decode(ctx, data, tx_irritate, rx_irritate):
         # Feed data to decoder
         tx_stall = random.randint(0, 1) if tx_irritate else False
 
-        if tx_done:
+        if tx_done or tx_stall:
             ctx.set(cd.sink.data, 0)
             ctx.set(cd.sink.valid, 0)
 
-        elif not tx_stall:
+        else:
             ctx.set(cd.sink.valid, 1)
             ctx.set(cd.sink.data, data[tx_index])