diff --git a/examples/08_gui_snapshot.rb b/examples/08_gui_snapshot.rb
index d582b0f..e06e523 100755
--- a/examples/08_gui_snapshot.rb
+++ b/examples/08_gui_snapshot.rb
@@ -68,7 +68,7 @@ class Gui < Gosu::Window
     own_tee = @tees[@client.local_client_id]
     own_tee = @tees.first.last if own_tee.nil?
     offset = center_around_tee(own_tee)
-    @tees.each do |_id, tee|
+    @tees.each_value do |tee|
       @tee_image.draw(tee.x + offset.x, tee.y + offset.y)
     end
   end
diff --git a/lib/array.rb b/lib/array.rb
index 90751d6..bf4c616 100644
--- a/lib/array.rb
+++ b/lib/array.rb
@@ -22,7 +22,7 @@ class Array
         group = []
       end
     end
-    groups.push(group) unless group.size.zero?
+    groups.push(group) unless group.empty?
     groups
   end
 end
diff --git a/lib/context.rb b/lib/context.rb
index 86f4b00..5dfac22 100644
--- a/lib/context.rb
+++ b/lib/context.rb
@@ -12,7 +12,7 @@ class Context
   end
 
   def verify
-    @data.each do |key, _value|
+    @data.each_key do |key|
       next if @old_data.key? key
 
       raise "Error: invalid data key '#{key}'\n       valid keys: #{@old_data.keys}"
diff --git a/lib/game_server.rb b/lib/game_server.rb
index 7cb441f..571e8bf 100644
--- a/lib/game_server.rb
+++ b/lib/game_server.rb
@@ -149,7 +149,7 @@ class GameServer
     return if call_hook(:shutdown, Context.new(nil)).nil?
 
     puts '[gameserver] disconnecting all clients ...'
-    @server.clients.each do |_id, client|
+    @server.clients.each_value do |client|
       @server.send_ctrl_close(client, @server.shutdown_reason)
     end
     puts '[gameserver] shutting down ...'
diff --git a/lib/snapshot/items/tune_params.rb b/lib/snapshot/items/tune_params.rb
index 8b65df1..edb41ef 100644
--- a/lib/snapshot/items/tune_params.rb
+++ b/lib/snapshot/items/tune_params.rb
@@ -25,7 +25,7 @@ class NetObj
     end
 
     def validate
-      @fields.select(&:nil?).empty?
+      @fields.none?(&:nil?)
     end
 
     def init_unpacker(u)
diff --git a/lib/snapshot/snap_item_base.rb b/lib/snapshot/snap_item_base.rb
index b65db25..486edde 100644
--- a/lib/snapshot/snap_item_base.rb
+++ b/lib/snapshot/snap_item_base.rb
@@ -22,7 +22,7 @@ class SnapItemBase
   end
 
   def validate
-    @fields.select(&:nil?).empty?
+    @fields.none?(&:nil?)
   end
 
   def init_unpacker(u)
diff --git a/lib/teeworlds_client.rb b/lib/teeworlds_client.rb
index 2791531..aba2b29 100644
--- a/lib/teeworlds_client.rb
+++ b/lib/teeworlds_client.rb
@@ -438,7 +438,7 @@ class TeeworldsClient
 
   def process_server_packet(packet)
     data = packet.payload
-    if data.size.zero?
+    if data.empty?
       puts 'Error: packet payload is empty'
       puts packet
       return
diff --git a/lib/teeworlds_server.rb b/lib/teeworlds_server.rb
index 93e3df3..d61ce3a 100644
--- a/lib/teeworlds_server.rb
+++ b/lib/teeworlds_server.rb
@@ -380,7 +380,7 @@ class TeeworldsServer
     # msg_snap_single = NetChunk.create_header(vital: false, size: data.size + 1) +
     #                  [pack_msg_id(NETMSG_SNAPSINGLE, system: true)] +
     #                  data
-    @clients.each do |_id, client|
+    @clients.each_value do |client|
       next unless client.in_game?
 
       @netbase.send_packet(msg_snap_empty, chunks: 1, client:)