diff --git a/moto/kinesis/responses.py b/moto/kinesis/responses.py
index d238f75d..839bf73e 100644
--- a/moto/kinesis/responses.py
+++ b/moto/kinesis/responses.py
@@ -18,7 +18,7 @@ class KinesisResponse(BaseResponse):
 
     @property
     def is_firehose(self):
-        host = self.headers.get('host', self.headers['Host'])
+        host = self.headers.get('host') or self.headers['Host']
         return host.startswith('firehose')
 
     def create_stream(self):