diff --git a/python/.changelog.d/1442.changed b/python/.changelog.d/1442.changed
new file mode 100644
index 000000000..8da49b99e
--- /dev/null
+++ b/python/.changelog.d/1442.changed
@@ -0,0 +1 @@
+Raise `ValueError` when the txid for an input is not present in `prev_txes` during `btc.sign_tx`
diff --git a/python/src/trezorlib/btc.py b/python/src/trezorlib/btc.py
index c8ae222e1..316e27be9 100644
--- a/python/src/trezorlib/btc.py
+++ b/python/src/trezorlib/btc.py
@@ -334,6 +334,10 @@ def sign_tx(
 
         # Device asked for one more information, let's process it.
         if res.details.tx_hash is not None:
+            if res.details.tx_hash not in prev_txes:
+                raise ValueError(
+                    f"Previous transaction {res.details.tx_hash.hex()} not available"
+                )
             current_tx = prev_txes[res.details.tx_hash]
         else:
             current_tx = this_tx