diff --git a/lib/xcodeproj/scheme/environment_variables.rb b/lib/xcodeproj/scheme/environment_variables.rb
index 09a340b7b..b7b3911a2 100644
--- a/lib/xcodeproj/scheme/environment_variables.rb
+++ b/lib/xcodeproj/scheme/environment_variables.rb
@@ -11,11 +11,10 @@ class XCScheme
     #
     class EnvironmentVariables < XMLElementWrapper
       # @param [nil,REXML::Element,Array<EnvironmentVariable>,Array<Hash{Symbol => String,Bool}>] node_or_variables
-      #   The 'EnvironmentVariables' XML node that this object represents. If nil, it will create a default XML
-      #   node to use.
-      # @note If initializing with an array of hashes, the hash should be of the form
-      #   {:key => <String>, :value => <String>(, :enabled => <Bool>)}.
-      # @see EnvironmentVariable#initialize
+      #   The 'EnvironmentVariables' XML node that this object represents.
+      #   - If nil, an empty 'EnvironmentVariables' XML node will be created
+      #   - If an REXML::Element, it must be named 'EnvironmentVariables'
+      #   - If an Array of objects or Hashes, they'll each be passed to {#assign_variable}
       #
       def initialize(node_or_variables = nil)
         create_xml_element_with_fallback(node_or_variables, VARIABLES_NODE) do
@@ -34,9 +33,9 @@ def all_variables
       # Adds a given variable to the set of environment variables, or replaces it if that key already exists
       #
       # @param [EnvironmentVariable,Hash{Symbol => String,Bool}] variable
-      #   The variable to set
-      # @note If initializing with an array of hashes, the hash should be of the form
-      #   {:key => <String>, :value => <String>(, :enabled => <Bool>)}.
+      #   The variable to add or update, backed by an EnvironmentVariable node.
+      #   - If an EnvironmentVariable, the previous reference should still be valid
+      #   - If a Hash, must contain keys :key and :value (Strings) and optionally :enabled (Boolean)
       # @see EnvironmentVariable#initialize
       # @return [Array<EnvironmentVariable>]
       #   The new set of environment variables after addition
@@ -62,6 +61,29 @@ def remove_variable(variable)
         @all_variables -= [env_var]
       end
 
+      # @param [String] key
+      #   The key to lookup
+      # @return [EnvironmentVariable] variable
+      #   Returns the matching environment variable for a specified key
+      #
+      def [](key)
+        all_variables.find { |var| var.key == key }
+      end
+
+      # Assigns a value for a specified key
+      #
+      # @param [String] key
+      #   The key to update in the environment variables
+      # @param [String] value
+      #   The value to lookup
+      # @return [EnvironmentVariable] variable
+      #   The newly updated environment variable
+      #
+      def []=(key, value)
+        assign_variable(:key => key, :value => value)
+        self[key]
+      end
+
       # @return Array<Hash{Symbol => String,Bool}>
       #   The current environment variables represented as an array
       #
diff --git a/spec/scheme/environment_variables_spec.rb b/spec/scheme/environment_variables_spec.rb
index cf23dc0a5..0237d79fd 100644
--- a/spec/scheme/environment_variables_spec.rb
+++ b/spec/scheme/environment_variables_spec.rb
@@ -159,6 +159,32 @@ def self.xml_for_object(object)
         subject.to_a.should == [:key => 'key1', :value => 'value1', :enabled => true]
       end
     end
+
+    describe '#[] and #[]=' do
+      element = REXML::Document.new('<EnvironmentVariables>' \
+          "<EnvironmentVariable key='key1' value='value1' isEnabled='NO'/>" \
+          '</EnvironmentVariables>').elements['EnvironmentVariables']
+      subject = XCScheme::EnvironmentVariables.new(element)
+
+      it 'updates an existing key if one exists, and automatically sets it to be enabled' do
+        subject['key1'].class.should == XCScheme::EnvironmentVariable
+        subject['key1'].to_h.should == { :key => 'key1', :value => 'value1', :enabled => false }
+
+        subject['key1'] = 'updated'
+        subject.all_variables.count.should == 1
+        subject['key1'].to_h.should == { :key => 'key1', :value => 'updated', :enabled => true }
+        Xcodeproj.xml_for_object(subject['key1']).should == "<EnvironmentVariable key='key1' value='updated' isEnabled='YES'/>"
+      end
+
+      it 'inserts a new key if a match does not already exists' do
+        subject['key2'].should.be.nil
+
+        subject['key2'] = 'inserted'
+        subject.all_variables.count.should == 2
+        subject['key2'].to_h.should == { :key => 'key2', :value => 'inserted', :enabled => true }
+        Xcodeproj.xml_for_object(subject['key2']).should == "<EnvironmentVariable key='key2' value='inserted' isEnabled='YES'/>"
+      end
+    end
   end
 
   describe XCScheme::EnvironmentVariable do