diff --git a/features/abbreviations_cn22.yml b/features/abbreviations_cn22.yml
new file mode 100644
index 0000000..b1e108c
--- /dev/null
+++ b/features/abbreviations_cn22.yml
@@ -0,0 +1,3 @@
+---
+user:
+  id: 1
diff --git a/features/file_s3.yml b/features/file_s3.yml
new file mode 100644
index 0000000..b1e108c
--- /dev/null
+++ b/features/file_s3.yml
@@ -0,0 +1,3 @@
+---
+user:
+  id: 1
diff --git a/features/s3_file.yml b/features/s3_file.yml
new file mode 100644
index 0000000..b1e108c
--- /dev/null
+++ b/features/s3_file.yml
@@ -0,0 +1,3 @@
+---
+user:
+  id: 1
diff --git a/lib/toggles/constant_lookup.rb b/lib/toggles/constant_lookup.rb
index 8107577..cafbf85 100644
--- a/lib/toggles/constant_lookup.rb
+++ b/lib/toggles/constant_lookup.rb
@@ -8,13 +8,13 @@ def initialize(sym)
     end
   end
 
-
   # Return a tree walker that translates Module#const_missing(sym) into the next child node
   #
   # So Features::Cat::BearDog walks as:
   # * next_features = Feature.features # root
   # * const_missing(:Cat) => next_features = next_features['cat']
   # * const_missing(:BearDog) => next_features['bear_dog']
+  # * const_missing(:CN22) => next_features['c_n_22']
   #
   # Defined at Toggles.features_dir + "/cat/bear_dog.yaml"
   #
@@ -22,21 +22,24 @@ def initialize(sym)
   def self.from(features, path)
     Class.new {
       class << self
-        attr_accessor :features
-        attr_accessor :path
+        attr_accessor :features, :path
 
         def const_missing(sym)
-          subtree_or_feature = features.fetch(
-            # translate class name into path part i.e :BearDog #=> 'bear_dog'
-            sym.to_s.gsub(/([a-z])([A-Z])/) { |s| s.chars.join('_') }.downcase.to_sym,
-          )
+          # translate class name into path part i.e :BearDog #=> 'bear_dog'
+          key = sym.to_s
+          key.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2'.freeze)
+          key.gsub!(/([a-z\d])([A-Z])/, '\1_\2'.freeze)
+          key.downcase!
+
+          subtree_or_feature = features.fetch(key.to_sym)
+
           if subtree_or_feature.is_a?(Hash)
             Feature::ConstantLookup.from(subtree_or_feature, path + [sym])
           else
             subtree_or_feature
           end
         rescue KeyError
-          raise Error.new(path + [sym])
+          raise Error, path + [sym]
         end
       end
     }.tap do |resolver|
diff --git a/lib/toggles/version.rb b/lib/toggles/version.rb
index b4a5875..0af0489 100644
--- a/lib/toggles/version.rb
+++ b/lib/toggles/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Toggles
-  VERSION = '0.3.0'
+  VERSION = '0.3.2'
 end
diff --git a/spec/toggles/feature/base_spec.rb b/spec/toggles/feature/base_spec.rb
index 1440401..07f5a74 100644
--- a/spec/toggles/feature/base_spec.rb
+++ b/spec/toggles/feature/base_spec.rb
@@ -2,9 +2,35 @@
   let(:user)   { double(id: 1, logged_in?: true) }
   let(:widget) { double(id: 2) }
 
-  subject { Feature::MultipleSubjects.new(user: user, widget: widget) }
+  context 'multiple subjects' do
+    subject { Feature::MultipleSubjects.new(user: user, widget: widget) }
 
-  its(:enabled?)              { is_expected.to eq true }
-  its(:subjects)              { is_expected.to eq user: user, widget: widget }
-  its("permissions.subjects") { is_expected.to eq [:user, :widget] }
+    its(:enabled?)              do is_expected.to eq true end
+    its(:subjects)              do is_expected.to eq user: user, widget: widget end
+    its('permissions.subjects') { is_expected.to eq %i[user widget] }
+  end
+
+  context 'abbreviation with numbers' do
+    subject { Feature::AbbreviationsCN22.new(user: user) }
+
+    its(:enabled?)              do is_expected.to eq true end
+    its(:subjects)              do is_expected.to eq user: user end
+    its('permissions.subjects') { is_expected.to eq [:user] }
+  end
+
+  context 'irregular capitalization' do
+    subject { Feature::S3File.new(user: user) }
+
+    its(:enabled?)              do is_expected.to eq true end
+    its(:subjects)              do is_expected.to eq user: user end
+    its('permissions.subjects') { is_expected.to eq [:user] }
+  end
+
+  context 'irregular capitalization' do
+    subject { Feature::FileS3.new(user: user) }
+
+    its(:enabled?)              do is_expected.to eq true end
+    its(:subjects)              do is_expected.to eq user: user end
+    its('permissions.subjects') { is_expected.to eq [:user] }
+  end
 end