diff --git a/docker-compose.yml b/docker-compose.yml
index a21b9d52..54d06d36 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -11,6 +11,8 @@ services:
     - 8.8.4.4
   redis:
     image: redis
+    ports:
+      - "6379:6379"
   tests:
     image: sidekiq-cron-test
     environment: *environment
diff --git a/lib/sidekiq/cron/job.rb b/lib/sidekiq/cron/job.rb
index 313f8db5..5e855cb0 100644
--- a/lib/sidekiq/cron/job.rb
+++ b/lib/sidekiq/cron/job.rb
@@ -461,7 +461,7 @@ def save
 
           #add information about last time! - don't enque right after scheduler poller starts!
           time = Time.now.utc
-          conn.zadd(job_enqueued_key, time.to_f.to_s, formated_last_time(time).to_s) unless conn.exists(job_enqueued_key)
+          conn.zadd(job_enqueued_key, time.to_f.to_s, formated_last_time(time).to_s) unless conn.exists?(job_enqueued_key)
         end
         logger.info { "Cron Jobs - add job with name: #{@name}" }
       end
@@ -540,7 +540,7 @@ def formated_last_time now = Time.now.utc
       def self.exists? name
         out = false
         Sidekiq.redis do |conn|
-          out = conn.exists redis_key name
+          out = conn.exists? redis_key name
         end
         out
       end
diff --git a/sidekiq-cron.gemspec b/sidekiq-cron.gemspec
index 5962d75d..e1575eb3 100644
--- a/sidekiq-cron.gemspec
+++ b/sidekiq-cron.gemspec
@@ -66,9 +66,10 @@ Gem::Specification.new do |s|
     if Gem::Version.new(Gem::VERSION) >= Gem::Version.new('1.2.0') then
       s.add_runtime_dependency(%q<sidekiq>.freeze, [">= 4.2.1"])
       s.add_runtime_dependency(%q<fugit>.freeze, ["~> 1.1"])
+      s.add_runtime_dependency(%q<redis>.freeze, [">= 4.2.0"])
       s.add_development_dependency(%q<bundler>.freeze, [">= 0"])
       s.add_development_dependency(%q<simplecov>.freeze, [">= 0"])
-      s.add_development_dependency(%q<redis-namespace>.freeze, [">= 1.5.2"])
+      s.add_development_dependency(%q<redis-namespace>.freeze, [">= 1.8.0"])
       s.add_development_dependency(%q<shoulda-context>.freeze, [">= 0"])
       s.add_development_dependency(%q<rack>.freeze, [">= 0"])
       s.add_development_dependency(%q<rack-test>.freeze, [">= 0"])
@@ -88,7 +89,8 @@ Gem::Specification.new do |s|
       s.add_dependency(%q<fugit>.freeze, ["~> 1.1"])
       s.add_dependency(%q<bundler>.freeze, [">= 0"])
       s.add_dependency(%q<simplecov>.freeze, [">= 0"])
-      s.add_dependency(%q<redis-namespace>.freeze, [">= 1.5.2"])
+      s.add_dependency(%q<redis>.freeze, [">= 4.2.0"])
+      s.add_dependency(%q<redis-namespace>.freeze, [">= 1.8.0"])
       s.add_dependency(%q<shoulda-context>.freeze, [">= 0"])
       s.add_dependency(%q<rack>.freeze, [">= 0"])
       s.add_dependency(%q<rack-test>.freeze, [">= 0"])
@@ -109,10 +111,11 @@ Gem::Specification.new do |s|
     s.add_dependency(%q<fugit>.freeze, ["~> 1.1"])
     s.add_dependency(%q<bundler>.freeze, [">= 0"])
     s.add_dependency(%q<simplecov>.freeze, [">= 0"])
-    s.add_dependency(%q<redis-namespace>.freeze, [">= 1.5.2"])
+    s.add_dependency(%q<redis-namespace>.freeze, [">= 1.8.0"])
     s.add_dependency(%q<shoulda-context>.freeze, [">= 0"])
     s.add_dependency(%q<rack>.freeze, [">= 0"])
     s.add_dependency(%q<rack-test>.freeze, [">= 0"])
+    s.add_dependency(%q<redis>.freeze, [">= 4.2.0"])
     s.add_dependency(%q<jeweler>.freeze, [">= 0"])
     s.add_dependency(%q<minitest>.freeze, [">= 0"])
     s.add_dependency(%q<test-unit>.freeze, [">= 0"])
@@ -126,4 +129,3 @@ Gem::Specification.new do |s|
     s.add_dependency(%q<guard-minitest>.freeze, [">= 0"])
   end
 end
-