diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed9beefbd4..4a5de17263 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,10 @@
 * [#136](https://github.com/rubocop-hq/rubocop-rails/pull/136): Fix a false positive for `Rails/ReversibleMigration` when using `change_default` with `:from` and `:to` options. ([@sinsoku][])
 * [#144](https://github.com/rubocop-hq/rubocop-rails/issues/144): Fix a false positive for `Rails/ReversibleMigration` when using `change_table_comment` or `change_column_comment` with a `:from` and `:to` hash. ([@DNA][])
 
+### Changes
+
+* [#156](https://github.com/rubocop-hq/rubocop-rails/pull/156): Make `Rails/UnknownEnv` cop aware of `Rails.env == 'unknown_env'`. ([@pocke][])
+
 ## 2.3.2 (2019-09-01)
 
 ### Bug fixes
diff --git a/lib/rubocop/cop/rails/unknown_env.rb b/lib/rubocop/cop/rails/unknown_env.rb
index b41f5148ec..3157603815 100644
--- a/lib/rubocop/cop/rails/unknown_env.rb
+++ b/lib/rubocop/cop/rails/unknown_env.rb
@@ -9,9 +9,11 @@ module Rails
       # @example
       #   # bad
       #   Rails.env.proudction?
+      #   Rails.env == 'proudction'
       #
       #   # good
       #   Rails.env.production?
+      #   Rails.env == 'production'
       class UnknownEnv < Cop
         include NameSimilarity
 
@@ -19,28 +21,43 @@ class UnknownEnv < Cop
         MSG_SIMILAR = 'Unknown environment `%<name>s`. ' \
                       'Did you mean `%<similar>s`?'
 
-        def_node_matcher :unknown_environment?, <<-PATTERN
+        def_node_matcher :rails_env?, <<~PATTERN
           (send
-            (send
-              {(const nil? :Rails) (const (cbase) :Rails)}
-              :env)
-            $#unknown_env_name?)
+            {(const nil? :Rails) (const (cbase) :Rails)}
+            :env)
+        PATTERN
+
+        def_node_matcher :unknown_environment_predicate?, <<~PATTERN
+          (send #rails_env? $#unknown_env_predicate?)
+        PATTERN
+
+        def_node_matcher :unknown_environment_equal?, <<-PATTERN
+          {
+            (send #rails_env? {:== :===} $(str #unknown_env_name?))
+            (send $(str #unknown_env_name?) {:== :===} #rails_env?)
+          }
         PATTERN
 
         def on_send(node)
-          unknown_environment?(node) do |name|
+          unknown_environment_predicate?(node) do |name|
             add_offense(node, location: :selector, message: message(name))
           end
+
+          unknown_environment_equal?(node) do |str_node|
+            name = str_node.value
+            add_offense(str_node, message: message(name))
+          end
         end
 
         private
 
         def collect_variable_like_names(_scope)
-          environments.map { |env| env + '?' }
+          environments
         end
 
         def message(name)
-          similar = find_similar_name(name.to_s, [])
+          name = name.to_s.chomp('?')
+          similar = find_similar_name(name, [])
           if similar
             format(MSG_SIMILAR, name: name, similar: similar)
           else
@@ -48,12 +65,16 @@ def message(name)
           end
         end
 
-        def unknown_env_name?(name)
+        def unknown_env_predicate?(name)
           name = name.to_s
           name.end_with?('?') &&
             !environments.include?(name[0..-2])
         end
 
+        def unknown_env_name?(name)
+          !environments.include?(name)
+        end
+
         def environments
           cop_config['Environments']
         end
diff --git a/manual/cops_rails.md b/manual/cops_rails.md
index 97b8e39e7a..9535247b70 100644
--- a/manual/cops_rails.md
+++ b/manual/cops_rails.md
@@ -2502,9 +2502,11 @@ exist.
 ```ruby
 # bad
 Rails.env.proudction?
+Rails.env == 'proudction'
 
 # good
 Rails.env.production?
+Rails.env == 'production'
 ```
 
 ### Configurable attributes
diff --git a/spec/rubocop/cop/rails/unknown_env_spec.rb b/spec/rubocop/cop/rails/unknown_env_spec.rb
index 696e473311..cbf344797c 100644
--- a/spec/rubocop/cop/rails/unknown_env_spec.rb
+++ b/spec/rubocop/cop/rails/unknown_env_spec.rb
@@ -14,19 +14,32 @@
   end
 
   it 'registers an offense for typo of environment name' do
-    expect_offense(<<-RUBY)
+    expect_offense(<<~RUBY)
       Rails.env.proudction?
-                ^^^^^^^^^^^ Unknown environment `proudction?`. Did you mean `production?`?
+                ^^^^^^^^^^^ Unknown environment `proudction`. Did you mean `production`?
       Rails.env.developpment?
-                ^^^^^^^^^^^^^ Unknown environment `developpment?`. Did you mean `development?`?
+                ^^^^^^^^^^^^^ Unknown environment `developpment`. Did you mean `development`?
       Rails.env.something?
-                ^^^^^^^^^^ Unknown environment `something?`.
+                ^^^^^^^^^^ Unknown environment `something`.
+    RUBY
+  end
+
+  it 'registers an offense for typo of environment name with `==` operator' do
+    expect_offense(<<~RUBY)
+      Rails.env == 'proudction'
+                   ^^^^^^^^^^^^ Unknown environment `proudction`. Did you mean `production`?
+      'developpment' == Rails.env
+      ^^^^^^^^^^^^^^ Unknown environment `developpment`. Did you mean `development`?
+
+      'something' === Rails.env
+      ^^^^^^^^^^^ Unknown environment `something`.
     RUBY
   end
 
   it 'accepts correct environment name' do
-    expect_no_offenses(<<-RUBY)
+    expect_no_offenses(<<~RUBY)
       Rails.env.production?
+      Rails.env == 'production'
     RUBY
   end
 end