diff --git a/src/borg/algorithms/msgpack/_packer.pyx b/src/borg/algorithms/msgpack/_packer.pyx
index c490a5b6c..2aba15105 100644
--- a/src/borg/algorithms/msgpack/_packer.pyx
+++ b/src/borg/algorithms/msgpack/_packer.pyx
@@ -1,5 +1,5 @@
 # coding: utf-8
-#cython: embedsignature=True, c_string_encoding=ascii
+#cython: embedsignature=True, c_string_encoding=ascii, language_level=2
 
 from cpython cimport *
 from cpython.version cimport PY_MAJOR_VERSION
diff --git a/src/borg/algorithms/msgpack/_unpacker.pyx b/src/borg/algorithms/msgpack/_unpacker.pyx
index 0abd9c101..79df33686 100644
--- a/src/borg/algorithms/msgpack/_unpacker.pyx
+++ b/src/borg/algorithms/msgpack/_unpacker.pyx
@@ -1,5 +1,5 @@
 # coding: utf-8
-#cython: embedsignature=True, c_string_encoding=ascii
+#cython: embedsignature=True, c_string_encoding=ascii, language_level=2
 
 from cpython.version cimport PY_MAJOR_VERSION
 from cpython.bytes cimport (
diff --git a/src/borg/platform/syncfilerange.pyx b/src/borg/platform/syncfilerange.pyx
index f3c57ef31..d578cab07 100644
--- a/src/borg/platform/syncfilerange.pyx
+++ b/src/borg/platform/syncfilerange.pyx
@@ -1,3 +1,5 @@
+# cython: language_level=3
+
 from libc.stdint cimport int64_t