diff --git a/acme/acme/challenges.py b/acme/acme/challenges.py
index 22bda6445..08d847627 100644
--- a/acme/acme/challenges.py
+++ b/acme/acme/challenges.py
@@ -245,7 +245,7 @@ class DNS01Response(KeyAuthorizationChallengeResponse):
             from acme import dns_resolver
             txt_records = dns_resolver.txt_records_for_name(
                 validation_domain_name)
-        except ImportError:
+        except ImportError:  # pragma: no cover
             raise ImportError("Local validation for 'dns-01' challenges "
                               "requires 'dnspython'")
         exists = validation in txt_records
diff --git a/acme/acme/dns_resolver.py b/acme/acme/dns_resolver.py
index 04e52224e..e28f132f1 100644
--- a/acme/acme/dns_resolver.py
+++ b/acme/acme/dns_resolver.py
@@ -19,7 +19,7 @@ def txt_records_for_name(name):
     """
     try:
         dns_response = dns.resolver.query(name, 'TXT')
-    except ImportError as error:
+    except ImportError as error:  # pragma: no cover
         raise ImportError("Local validation for 'dns-01' challenges requires "
                           "'dnspython'")
     except dns.exception.DNSException as error:
diff --git a/tox.ini b/tox.ini
index cdc2c2396..c0a819b5e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,7 +15,7 @@ envlist = py26,py27,py33,py34,py35,cover,lint
 # packages installed separately to ensure that dowstream deps problems
 # are detected, c.f. #1002
 commands =
-    pip install -e acme[testing]
+    pip install -e acme[dns,testing]
     nosetests -v acme
     pip install -e .[testing]
     nosetests -v letsencrypt
@@ -33,17 +33,17 @@ setenv =
 
 [testenv:py33]
 commands =
-    pip install -e acme[dev,testing]
+    pip install -e acme[dns,testing]
     nosetests -v acme
 
 [testenv:py34]
 commands =
-    pip install -e acme[dev,testing]
+    pip install -e acme[dns,testing]
     nosetests -v acme
 
 [testenv:py35]
 commands =
-    pip install -e acme[dev,testing]
+    pip install -e acme[dns,testing]
     nosetests -v acme
 
 [testenv:cover]