diff --git a/docker/constants.py b/docker/constants.py
index 0bfc0b08..4337fedc 100644
--- a/docker/constants.py
+++ b/docker/constants.py
@@ -2,7 +2,7 @@ import sys
 from .version import version
 
 DEFAULT_DOCKER_API_VERSION = '1.24'
-MINIMUM_DOCKER_API_VERSION = '1.24'
+MINIMUM_DOCKER_API_VERSION = '1.21'
 DEFAULT_TIMEOUT_SECONDS = 60
 STREAM_HEADER_SIZE_BYTES = 8
 CONTAINER_LIMITS_KEYS = [