diff --git a/lib/sidekiq/cli.rb b/lib/sidekiq/cli.rb
index d3e5ff0eb..afa236278 100644
--- a/lib/sidekiq/cli.rb
+++ b/lib/sidekiq/cli.rb
@@ -27,7 +27,7 @@ class CLI
     attr_accessor :launcher
     attr_accessor :environment
 
-    def parse(args=ARGV)
+    def parse(args = ARGV)
       setup_options(args)
       initialize_logger
       validate!
@@ -227,17 +227,33 @@ def symbolize_keys_deep!(hash)
     alias_method :☠, :exit
 
     def setup_options(args)
+      # parse CLI options
       opts = parse_options(args)
+
       set_environment opts[:environment]
 
-      options[:queues] << 'default' if options[:queues].empty?
+      # check config file presence
+      if opts[:config_file]
+        if opts[:config_file] && !File.exist?(opts[:config_file])
+          raise ArgumentError, "No such file #{opts[:config_file]}"
+        end
+      else
+        if File.directory?(opts[:require])
+          %w[config/sidekiq.yml config/sidekiq.yml.erb].each do |filename|
+            path = File.expand_path(filename, opts[:require])
+            opts[:config_file] ||= path if File.exist?(path)
+          end
+        end
+      end
 
-      cfile = opts[:config_file]
-      opts = parse_config(cfile).merge(opts) if cfile
+      # parse config file options
+      opts = parse_config(opts[:config_file]).merge(opts) if opts[:config_file]
 
+      opts[:queues] = Array(opts[:queues]) << 'default' if opts[:queues].nil? || opts[:queues].empty?
       opts[:strict] = true if opts[:strict].nil?
-      opts[:concurrency] = Integer(ENV["RAILS_MAX_THREADS"]) if !opts[:concurrency] && ENV["RAILS_MAX_THREADS"]
+      opts[:concurrency] = Integer(ENV["RAILS_MAX_THREADS"]) if opts[:concurrency].nil? && ENV["RAILS_MAX_THREADS"]
 
+      # merge with defaults
       options.merge!(opts)
     end
 
@@ -367,11 +383,8 @@ def parse_options(argv)
         logger.info @parser
         die 1
       end
-      @parser.parse!(argv)
 
-      %w[config/sidekiq.yml config/sidekiq.yml.erb].each do |filename|
-        opts[:config_file] ||= filename if File.exist?(filename)
-      end
+      @parser.parse!(argv)
 
       opts
     end
@@ -391,23 +404,18 @@ def write_pid
       end
     end
 
-    def parse_config(cfile)
-      opts = {}
-      if File.exist?(cfile)
-        opts = YAML.load(ERB.new(IO.read(cfile)).result) || opts
+    def parse_config(path)
+      opts = YAML.load(ERB.new(File.read(path)).result) || {}
 
-        if opts.respond_to? :deep_symbolize_keys!
-          opts.deep_symbolize_keys!
-        else
-          symbolize_keys_deep!(opts)
-        end
-
-        opts = opts.merge(opts.delete(environment.to_sym) || {})
-        parse_queues(opts, opts.delete(:queues) || [])
+      if opts.respond_to? :deep_symbolize_keys!
+        opts.deep_symbolize_keys!
       else
-        # allow a non-existent config file so Sidekiq
-        # can be deployed by cap with just the defaults.
+        symbolize_keys_deep!(opts)
       end
+
+      opts = opts.merge(opts.delete(environment.to_sym) || {})
+      parse_queues(opts, opts.delete(:queues) || [])
+
       ns = opts.delete(:namespace)
       if ns
         # logger hasn't been initialized yet, puts is all we have.
@@ -421,10 +429,10 @@ def parse_queues(opts, queues_and_weights)
       queues_and_weights.each { |queue_and_weight| parse_queue(opts, *queue_and_weight) }
     end
 
-    def parse_queue(opts, q, weight=nil)
+    def parse_queue(opts, queue, weight = nil)
       opts[:queues] ||= []
-      raise ArgumentError, "queues: #{q} cannot be defined twice" if opts[:queues].include?(q)
-      [weight.to_i, 1].max.times { opts[:queues] << q }
+      raise ArgumentError, "queues: #{queue} cannot be defined twice" if opts[:queues].include?(queue)
+      [weight.to_i, 1].max.times { opts[:queues] << queue }
       opts[:strict] = false if weight.to_i > 0
     end
   end
diff --git a/test/dummy/config/sidekiq.yml b/test/dummy/config/sidekiq.yml
new file mode 100644
index 000000000..774e4c88f
--- /dev/null
+++ b/test/dummy/config/sidekiq.yml
@@ -0,0 +1,2 @@
+---
+:concurrency: 25
diff --git a/test/test_cli.rb b/test/test_cli.rb
index 9fea92f5f..07aa95729 100644
--- a/test/test_cli.rb
+++ b/test/test_cli.rb
@@ -244,6 +244,17 @@ class TestCLI < Minitest::Test
             assert_equal 3, Sidekiq.options[:queues].count { |q| q == 'seldom' }
           end
         end
+
+        describe 'default config file' do
+          describe 'when required path is a directory' do
+            it 'tries config/sidekiq.yml' do
+              @cli.parse(%w[sidekiq -r ./test/dummy])
+
+              assert_equal 'sidekiq.yml', File.basename(Sidekiq.options[:config_file])
+              assert_equal 25, Sidekiq.options[:concurrency]
+            end
+          end
+        end
       end
     end
 
@@ -260,6 +271,14 @@ class TestCLI < Minitest::Test
           exit = assert_raises(SystemExit) { @cli.parse(%w[sidekiq -r ./test/fixtures]) }
           assert_equal 1, exit.status
         end
+
+        describe 'when config file path does not exist' do
+          it 'raises argument error' do
+            assert_raises(ArgumentError) do
+              @cli.parse(%w[sidekiq -r ./test/fake_env.rb -C /non/existent/path])
+            end
+          end
+        end
       end
     end
   end
@@ -277,7 +296,7 @@ class TestCLI < Minitest::Test
     after do
       Sidekiq.logger = @logger
     end
-    
+
     describe 'pidfile' do
       it 'writes process pid to file' do
         Sidekiq.options[:pidfile] = '/tmp/sidekiq.pid'