diff --git a/vertica_python/vertica/connection.py b/vertica_python/vertica/connection.py
index d0c64479..44aedc21 100644
--- a/vertica_python/vertica/connection.py
+++ b/vertica_python/vertica/connection.py
@@ -332,7 +332,7 @@ def __init__(self, options=None):
         self.startup_connection()
 
         # Complex types metadata is returned since protocol version 3.12
-        self.complex_types_enabled = self.parameters['protocol_version'] >= (3 << 16 | 12) and \
+        self.complex_types_enabled = self.parameters.get('protocol_version', 0) >= (3 << 16 | 12) and \
                                      self.parameters.get('request_complex_types', 'off') == 'on'
 
         self._logger.info('Connection is ready')