diff --git a/python/.changelog.d/+4afd8b1d.fixed b/python/.changelog.d/+4afd8b1d.fixed
new file mode 100644
index 0000000000..d10815d33a
--- /dev/null
+++ b/python/.changelog.d/+4afd8b1d.fixed
@@ -0,0 +1 @@
+Use `frozenset` for `models.TREZORS` to prevent accidental modification.
diff --git a/python/src/trezorlib/models.py b/python/src/trezorlib/models.py
index 2fde03eb2d..b1d638a6fd 100644
--- a/python/src/trezorlib/models.py
+++ b/python/src/trezorlib/models.py
@@ -109,7 +109,7 @@ TREZOR_SAFE5 = T3T1
 TREZOR_DISC1 = DISC1
 TREZOR_DISC2 = DISC2
 
-TREZORS = {T1B1, T2T1, T2B1, T3T1, T3B1, DISC1, DISC2}
+TREZORS = frozenset({T1B1, T2T1, T2B1, T3T1, T3B1, DISC1, DISC2})
 
 
 def by_name(name: Optional[str]) -> Optional[TrezorModel]: