diff --git a/pureboot/pureboot.py b/pureboot/pureboot.py
index 54332ac..6a8308b 100644
--- a/pureboot/pureboot.py
+++ b/pureboot/pureboot.py
@@ -497,8 +497,20 @@ class OneWirePort:
             raise Error(f"one-wire echo missing after {len(data) - len(remaining)} of "
                         f"{len(data)} byte(s) — is the adapter's RX tied to the line?")
         self.lost_echoes += len(remaining)
-        verbose(f"one-wire: {len(remaining)} of {len(data)} knock byte(s) lost to the "
-                f"device's ack; retrying")
+        # Which loss this is matters, and the count says it. *Some* bytes lost is
+        # the device's ack winning the line against the host's series resistor —
+        # ordinary, and what the retry absorbs. *Every* byte lost is nothing
+        # coming back at all, which is a line that is not free: an application
+        # holding the shared pin low (this rig's LED demo ends that way), a
+        # wedge, or an RX that is not on the line. Same retry either way, but
+        # blaming an ack that never happened sends the reader to the wrong place.
+        if len(remaining) == len(data):
+            verbose(f"one-wire: none of {len(data)} byte(s) echoed — the line is not "
+                    f"coming back. Held low by something? (a pin driven low, a wedge, "
+                    f"or an RX not on the line)")
+        else:
+            verbose(f"one-wire: {len(remaining)} of {len(data)} knock byte(s) lost to the "
+                    f"device's ack; retrying")
 
     def write_blind(self, data):
         self.write(data, blind=True)