diff --git a/pygeoapi/flask_app.py b/pygeoapi/flask_app.py
index 74b032c95..f2fceaa7a 100644
--- a/pygeoapi/flask_app.py
+++ b/pygeoapi/flask_app.py
@@ -43,9 +43,6 @@
 from pygeoapi.util import get_mimetype, get_api_rules
 
 
-if 'PYGEOAPI_OPENAPI' not in os.environ:
-    raise RuntimeError('PYGEOAPI_OPENAPI environment variable not set')
-
 CONFIG = get_config()
 OPENAPI = load_openapi_document()