diff --git a/core/src/apps/bitcoin/sign_tx/change_detector.py b/core/src/apps/bitcoin/sign_tx/change_detector.py
index ae8995846f..3f88e52c5e 100644
--- a/core/src/apps/bitcoin/sign_tx/change_detector.py
+++ b/core/src/apps/bitcoin/sign_tx/change_detector.py
@@ -17,15 +17,11 @@ _BIP32_MAX_LAST_ELEMENT = const(1_000_000)
 class ChangeDetector:
     def __init__(self) -> None:
         from .matchcheck import (
-            MultisigChecker,
             MultisigFingerprintChecker,
             ScriptTypeChecker,
             WalletPathChecker,
         )
 
-        # Whether all inputs are multisig or all inputs are singlesig, used to validate change-output.
-        self.multisig = MultisigChecker()
-
         # Checksum of multisig inputs, used to validate change-output.
         self.multisig_fingerprint = MultisigFingerprintChecker()
 
@@ -40,37 +36,30 @@ class ChangeDetector:
             self.wallet_path.add_input(txi)
             self.script_type.add_input(txi)
             self.multisig_fingerprint.add_input(txi)
-            self.multisig.add_input(txi)
 
     def check_input(self, txi: TxInput) -> None:
         self.wallet_path.check_input(txi)
         self.script_type.check_input(txi)
         self.multisig_fingerprint.check_input(txi)
-        self.multisig.check_input(txi)
 
     def output_is_change(self, txo: TxOutput) -> bool:
         if txo.script_type not in common.CHANGE_OUTPUT_SCRIPT_TYPES:
             return False
 
-        if txo.multisig:
-            if not (
-                self.multisig_fingerprint.output_matches(txo)
-                and common.multisig_uses_single_path(
-                    txo.multisig
-                )  # An address that uses different derivation paths for different xpubs
-                # could be difficult to discover if the user did not note all the paths.
-                # The reason is that each path ends with an address index, which can
-                # have 1,000,000 possible values. If the address is a t-out-of-n
-                # multisig, the total number of possible paths is 1,000,000^n. This can
-                # be exploited by an attacker who has compromised the user's computer.
-                # The attacker could randomize the address indices and then demand a
-                # ransom from the user to reveal the paths. To prevent this, we require
-                # that all xpubs use the same derivation path.
-            ):
-                return False
+        if txo.multisig and not common.multisig_uses_single_path(txo.multisig):
+            # An address that uses different derivation paths for different xpubs
+            # could be difficult to discover if the user did not note all the paths.
+            # The reason is that each path ends with an address index, which can
+            # have 1,000,000 possible values. If the address is a t-out-of-n
+            # multisig, the total number of possible paths is 1,000,000^n. This can
+            # be exploited by an attacker who has compromised the user's computer.
+            # The attacker could randomize the address indices and then demand a
+            # ransom from the user to reveal the paths. To prevent this, we require
+            # that all xpubs use the same derivation path.
+            return False
 
         return (
-            self.multisig.output_matches(txo)
+            self.multisig_fingerprint.output_matches(txo)
             and self.wallet_path.output_matches(txo)
             and self.script_type.output_matches(txo)
             and len(txo.address_n) >= common.BIP32_WALLET_DEPTH
diff --git a/core/src/apps/bitcoin/sign_tx/matchcheck.py b/core/src/apps/bitcoin/sign_tx/matchcheck.py
index 3cedb75034..1acb812cef 100644
--- a/core/src/apps/bitcoin/sign_tx/matchcheck.py
+++ b/core/src/apps/bitcoin/sign_tx/matchcheck.py
@@ -103,15 +103,14 @@ class MultisigFingerprintChecker(MatchChecker):
         from .. import multisig
 
         if not txio.multisig:
-            return None
+            # The fingerprint of a singlesig input or output is defined as an empty byte string.
+            # This has two consequences: First, a singlesig output matches if and only if all
+            # the added inputs are singlesig. Second, a multisig output does not match if any of
+            # the added inputs is singlesig.
+            return bytes()
         return multisig.multisig_fingerprint(txio.multisig)
 
 
-class MultisigChecker(MatchChecker):
-    def attribute_from_tx(self, txio: TxInput | TxOutput) -> Any:
-        return txio.multisig is not None
-
-
 class ScriptTypeChecker(MatchChecker):
     def attribute_from_tx(self, txio: TxInput | TxOutput) -> Any:
         from trezor.enums import InputScriptType