diff --git a/lib/spack/spack/config.py b/lib/spack/spack/config.py
index 6ef79c70b15c4e3ec94205c488cf1a9269b2964f..14e5aaf4fb624e9532e56b2f2a2f60669b8b3152 100644
--- a/lib/spack/spack/config.py
+++ b/lib/spack/spack/config.py
@@ -249,7 +249,7 @@
                 'default': {},
                 'additionalProperties': False,
                 'properties': {
-                    'disable': {
+                    'enable': {
                         'type': 'array',
                         'default': [],
                         'items': {
diff --git a/lib/spack/spack/modules.py b/lib/spack/spack/modules.py
index d354c8bb715976f255f873740af8bf903c07af5b..6c32937c3ccd1feb66ef1202f416ecea60346024 100644
--- a/lib/spack/spack/modules.py
+++ b/lib/spack/spack/modules.py
@@ -57,13 +57,8 @@
 # Registry of all types of modules.  Entries created by EnvModule's metaclass
 module_types = {}
 
+CONFIGURATION = spack.config.get_config('modules')
 
-def read_configuration_file():
-    f = spack.config.get_config('modules')
-    f.setdefault('disable', [])  # Default : disable nothing
-    return f
-
-CONFIGURATION = read_configuration_file()
 
 def print_help():
     """For use by commands to tell user how to activate shell support."""
@@ -123,7 +118,7 @@ class EnvModule(object):
     class __metaclass__(type):
         def __init__(cls, name, bases, dict):
             type.__init__(cls, name, bases, dict)
-            if cls.name != 'env_module' and cls.name not in CONFIGURATION['disable']:
+            if cls.name != 'env_module' and cls.name in CONFIGURATION['enable']:
                 module_types[cls.name] = cls
 
     def __init__(self, spec=None):