diff --git a/setup.py b/setup.py
index 5ef1031e..d604007e 100644
--- a/setup.py
+++ b/setup.py
@@ -30,7 +30,7 @@
     'scrapyd-client>=1.0.1',
     'six>=1.9.0',
     'requests~=2.22,>=2.22.0',
-    'celery~=4.2',
+    'celery>=4.1',
     'redis>=2.10.5',
     'pyasn1>=0.1.8',  # Needed for dependency resolving.
     'LinkHeader>=0.4.3',
diff --git a/tests/Dockerfile.hepcrawl_base b/tests/Dockerfile.hepcrawl_base
index 8db9f43e..bd43748b 100644
--- a/tests/Dockerfile.hepcrawl_base
+++ b/tests/Dockerfile.hepcrawl_base
@@ -7,7 +7,7 @@
 # under the terms of the Revised BSD License; see LICENSE file for
 # more details.
 
-FROM centos
+FROM centos:7
 
 RUN yum install -y epel-release && \
     yum update -y && \