diff --git a/python/src/trezorlib/client.py b/python/src/trezorlib/client.py
index 49b399d97d..fccddaf085 100644
--- a/python/src/trezorlib/client.py
+++ b/python/src/trezorlib/client.py
@@ -132,9 +132,9 @@ class TrezorClient:
         self.session_counter += 1
 
     def close(self):
-        if self.session_counter == 1:
+        self.session_counter = max(self.session_counter - 1, 0)
+        if self.session_counter == 0:
             self.transport.end_session()
-        self.session_counter -= 1
 
     def cancel(self):
         self._raw_write(messages.Cancel())
diff --git a/python/src/trezorlib/transport/protocol.py b/python/src/trezorlib/transport/protocol.py
index 8bee47374d..92afcfb3db 100644
--- a/python/src/trezorlib/transport/protocol.py
+++ b/python/src/trezorlib/transport/protocol.py
@@ -93,9 +93,9 @@ class Protocol:
         self.session_counter += 1
 
     def end_session(self) -> None:
-        if self.session_counter == 1:
+        self.session_counter = max(self.session_counter - 1, 0)
+        if self.session_counter == 0:
             self.handle.close()
-        self.session_counter -= 1
 
     def read(self) -> protobuf.MessageType:
         raise NotImplementedError