diff --git a/setup.py b/setup.py
index 4ee5657..d208eac 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@ version = meta['version']
 
 # Please update tox.ini when modifying dependency version requirements
 install_requires = [
-    'acme=={0}'.format(version),
+    'acme>=0.5.0',
     # 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.