diff --git a/tasks/swarm_init.rb b/tasks/swarm_init.rb
index f557d7c..78c49af 100755
--- a/tasks/swarm_init.rb
+++ b/tasks/swarm_init.rb
@@ -1,43 +1,43 @@
 #!/opt/puppetlabs/puppet/bin/ruby
 # frozen_string_literal: true
 
 require 'json'
 require 'open3'
 require 'puppet'
 
 def swarm_init(advertise_addr, autolock, cert_expiry, dispatcher_heartbeat, external_ca, force_new_cluster, listen_addr, max_snapshots, snapshot_interval)
   cmd_string = 'docker swarm init'
-  cmd_string << " --advertise-addr=#{advertise_addr}" unless advertise_addr.nil?
-  cmd_string << ' --autolock' unless autolock.nil?
-  cmd_string << ' --cert-expiry' unless cert_expiry.nil?
-  cmd_string << " --dispatcher-heartbeat=#{dispatcher_heartbeat}" unless dispatcher_heartbeat.nil?
-  cmd_string << " --external-ca=#{external_ca}" unless external_ca.nil?
-  cmd_string << ' --force-new-cluster' unless force_new_cluster.nil?
-  cmd_string << " --listen-addr=#{listen_addr}" unless listen_addr.nil?
-  cmd_string << " --max-snapshots=#{max_snapshots}" unless max_snapshots.nil?
-  cmd_string << " --snapshot-interval=#{snapshot_interval}" unless snapshot_interval.nil?
+  cmd_string += " --advertise-addr=#{advertise_addr}" unless advertise_addr.nil?
+  cmd_string += ' --autolock' unless autolock.nil?
+  cmd_string += ' --cert-expiry' unless cert_expiry.nil?
+  cmd_string += " --dispatcher-heartbeat=#{dispatcher_heartbeat}" unless dispatcher_heartbeat.nil?
+  cmd_string += " --external-ca=#{external_ca}" unless external_ca.nil?
+  cmd_string += ' --force-new-cluster' unless force_new_cluster.nil?
+  cmd_string += " --listen-addr=#{listen_addr}" unless listen_addr.nil?
+  cmd_string += " --max-snapshots=#{max_snapshots}" unless max_snapshots.nil?
+  cmd_string += " --snapshot-interval=#{snapshot_interval}" unless snapshot_interval.nil?
 
   stdout, stderr, status = Open3.capture3(cmd_string)
   raise Puppet::Error, "stderr: '#{stderr}'" if status != 0
   stdout.strip
 end
 
 params = JSON.parse(STDIN.read)
 advertise_addr = params['advertise_addr']
 autolock = params['autolock']
 cert_expiry = params['cert_expiry']
 dispatcher_heartbeat = params['dispatcher_heartbeat']
 external_ca = params['external_ca']
 force_new_cluster = params['force_new_cluster']
 listen_addr = params['listen_addr']
 max_snapshots = params['max_snapshots']
 snapshot_interval = params['snapshot_interval']
 
 begin
   result = swarm_init(advertise_addr, autolock, cert_expiry, dispatcher_heartbeat, external_ca, force_new_cluster, listen_addr, max_snapshots, snapshot_interval)
   puts result
   exit 0
 rescue Puppet::Error => e
   puts(status: 'failure', error: e.message)
   exit 1
 end
diff --git a/tasks/swarm_join.rb b/tasks/swarm_join.rb
index fcffa4c..c98471d 100755
--- a/tasks/swarm_join.rb
+++ b/tasks/swarm_join.rb
@@ -1,33 +1,33 @@
 #!/opt/puppetlabs/puppet/bin/ruby
 # frozen_string_literal: true
 
 require 'json'
 require 'open3'
 require 'puppet'
 
 def swarm_join(advertise_addr, listen_addr, token, manager_ip)
   cmd_string = 'docker swarm join'
-  cmd_string << " --advertise-addr=#{advertise_addr}" unless advertise_addr.nil?
-  cmd_string << " --listen-addr=#{listen_addr}" unless listen_addr.nil?
-  cmd_string << " --token=#{token}" unless token.nil?
-  cmd_string << " #{manager_ip}" unless manager_ip.nil?
+  cmd_string += " --advertise-addr=#{advertise_addr}" unless advertise_addr.nil?
+  cmd_string += " --listen-addr=#{listen_addr}" unless listen_addr.nil?
+  cmd_string += " --token=#{token}" unless token.nil?
+  cmd_string += " #{manager_ip}" unless manager_ip.nil?
 
   stdout, stderr, status = Open3.capture3(cmd_string)
   raise Puppet::Error, "stderr: '#{stderr}'" if status != 0
   stdout.strip
 end
 
 params = JSON.parse(STDIN.read)
 advertise_addr = params['advertise_addr']
 listen_addr = params['listen_addr']
 token = params['token']
 manager_ip = params['manager_ip']
 
 begin
   result = swarm_join(advertise_addr, listen_addr, token, manager_ip)
   puts result
   exit 0
 rescue Puppet::Error => e
   puts(status: 'failure', error: e.message)
   exit 1
 end
diff --git a/tasks/swarm_leave.rb b/tasks/swarm_leave.rb
index a5abefa..d6bc6bb 100755
--- a/tasks/swarm_leave.rb
+++ b/tasks/swarm_leave.rb
@@ -1,25 +1,25 @@
 #!/opt/puppetlabs/puppet/bin/ruby
 # frozen_string_literal: true
 
 require 'json'
 require 'open3'
 require 'puppet'
 
 def swarm_leave(force)
   cmd_string = 'docker swarm leave '
-  cmd_string << ' -f' if force == 'true'
+  cmd_string += ' -f' if force == 'true'
   stdout, stderr, status = Open3.capture3(cmd_string)
   raise Puppet::Error, "stderr: '#{stderr}'" if status != 0
   stdout.strip
 end
 
 params = JSON.parse(STDIN.read)
 force = params['force']
 begin
   result = swarm_leave(force)
   puts result
   exit 0
 rescue Puppet::Error => e
   puts(status: 'failure', error: e.message)
   exit 1
 end
diff --git a/tasks/swarm_update.rb b/tasks/swarm_update.rb
index 214c2e3..627923d 100755
--- a/tasks/swarm_update.rb
+++ b/tasks/swarm_update.rb
@@ -1,29 +1,29 @@
 #!/opt/puppetlabs/puppet/bin/ruby
 # frozen_string_literal: true
 
 require 'json'
 require 'open3'
 require 'puppet'
 
 def swarm_update(image, service)
   cmd_string = 'docker service update'
-  cmd_string << " --image #{image}" unless image.nil?
-  cmd_string << " #{service}" unless service.nil?
+  cmd_string += " --image #{image}" unless image.nil?
+  cmd_string += " #{service}" unless service.nil?
 
   stdout, stderr, status = Open3.capture3(cmd_string)
   raise Puppet::Error, "stderr: '#{stderr}'" if status != 0
   stdout.strip
 end
 
 params = JSON.parse(STDIN.read)
 image = params['image']
 service = params['service']
 
 begin
   result = swarm_update(image, service)
   puts result
   exit 0
 rescue Puppet::Error => e
   puts(status: 'failure', error: e.message)
   exit 1
 end