diff --git a/moto/awslambda/responses.py b/moto/awslambda/responses.py
index ce6c93f16..28b0e74fd 100644
--- a/moto/awslambda/responses.py
+++ b/moto/awslambda/responses.py
@@ -184,9 +184,9 @@ class LambdaResponse(BaseResponse):
             function_name, qualifier, self.body, self.headers, response_headers
         )
         if payload:
-            if request.headers["X-Amz-Invocation-Type"] == "Event":
+            if request.headers.get("X-Amz-Invocation-Type") == "Event":
                 status_code = 202
-            elif request.headers["X-Amz-Invocation-Type"] == "DryRun":
+            elif request.headers.get("X-Amz-Invocation-Type") == "DryRun":
                 status_code = 204
             else:
                 status_code = 200