diff --git a/certbot-nginx/setup.py b/certbot-nginx/setup.py
index af44a017a..fb5ad7a99 100644
--- a/certbot-nginx/setup.py
+++ b/certbot-nginx/setup.py
@@ -11,8 +11,8 @@ install_requires = [
     # This plugin works with an older version of acme, but Certbot does not.
     # 0.22.0 is specified here to work around
     # https://github.com/pypa/pip/issues/988.
-    'acme>=0.22.0',
-    'certbot>=0.22.0',
+    'acme>0.21.1',
+    'certbot>0.21.1',
     'mock',
     'PyOpenSSL',
     'pyparsing>=1.5.5',  # Python3 support; perhaps unnecessary?
diff --git a/setup.py b/setup.py
index 56eebbe75..e349bbe4a 100644
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@ version = meta['version']
 # specified here to avoid masking the more specific request requirements in
 # acme. See https://github.com/pypa/pip/issues/988 for more info.
 install_requires = [
-    'acme>=0.22.0',
+    'acme>0.21.1',
     # We technically need ConfigArgParse 0.10.0 for Python 2.6 support, but
     # saying so here causes a runtime error against our temporary fork of 0.9.3
     # in which we added 2.6 support (see #2243), so we relax the requirement.