diff --git a/mapping_provider/backends/rmq/exchange.py b/mapping_provider/backends/rmq/exchange.py
index d75aae37060d1cbfb410ef0b15de31a59adfe5b7..ef3f5fe004d2a4e396e9ea4195518746bb3b76c7 100644
--- a/mapping_provider/backends/rmq/exchange.py
+++ b/mapping_provider/backends/rmq/exchange.py
@@ -196,9 +196,9 @@ class RabbitMQClient:
         self.exchange_type = exchange_type
 
         self.routing_keys: Sequence[str] = []  # for mypy
-        if routing_keys is not None:
+        if routing_keys is None:
             self.routing_keys = []
-        if isinstance(routing_keys, str):
+        elif isinstance(routing_keys, str):
             self.routing_keys = [routing_keys]
         elif isinstance(routing_keys, Sequence):
             self.routing_keys = routing_keys