diff --git a/lib/slack/web/api/endpoints/chat.rb b/lib/slack/web/api/endpoints/chat.rb
index 9de4aa9..8ed5625 100644
--- a/lib/slack/web/api/endpoints/chat.rb
+++ b/lib/slack/web/api/endpoints/chat.rb
@@ -121,11 +121,22 @@ module Slack
           # @see https://api.slack.com/methods/chat.postEphemeral
           # @see https://github.com/slack-ruby/slack-api-ref/blob/master/methods/chat/chat.postEphemeral.json
           def chat_postEphemeral(options = {})
-            throw ArgumentError.new('Required arguments :attachments missing') if options[:attachments].nil?
             throw ArgumentError.new('Required arguments :channel missing') if options[:channel].nil?
-            throw ArgumentError.new('Required arguments :text missing') if options[:text].nil?
+            throw ArgumentError.new('Required arguments :text, :attachments or :blocks missing') if options[:text].nil? && options[:attachments].nil? && options[:blocks].nil?
             throw ArgumentError.new('Required arguments :user missing') if options[:user].nil?
             options = options.merge(user: users_id(options)['user']['id']) if options[:user]
+            # attachments must be passed as an encoded JSON string
+            if options.key?(:attachments)
+              attachments = options[:attachments]
+              attachments = JSON.dump(attachments) unless attachments.is_a?(String)
+              options = options.merge(attachments: attachments)
+            end
+            # blocks must be passed as an encoded JSON string
+            if options.key?(:blocks)
+              blocks = options[:blocks]
+              blocks = JSON.dump(blocks) unless blocks.is_a?(String)
+              options = options.merge(blocks: blocks)
+            end
             post('chat.postEphemeral', options)
           end

@@ -166,7 +177,19 @@ module Slack
           # @see https://github.com/slack-ruby/slack-api-ref/blob/master/methods/chat/chat.postMessage.json
           def chat_postMessage(options = {})
             throw ArgumentError.new('Required arguments :channel missing') if options[:channel].nil?
-            throw ArgumentError.new('Required arguments :text missing') if options[:text].nil?
+            throw ArgumentError.new('Required arguments :text, :attachments or :blocks missing') if options[:text].nil? && options[:attachments].nil? && options[:blocks].nil?
+            # attachments must be passed as an encoded JSON string
+            if options.key?(:attachments)
+              attachments = options[:attachments]
+              attachments = JSON.dump(attachments) unless attachments.is_a?(String)
+              options = options.merge(attachments: attachments)
+            end
+            # blocks must be passed as an encoded JSON string
+            if options.key?(:blocks)
+              blocks = options[:blocks]
+              blocks = JSON.dump(blocks) unless blocks.is_a?(String)
+              options = options.merge(blocks: blocks)
+            end
             post('chat.postMessage', options)
           end

@@ -254,8 +277,21 @@ module Slack
           # @see https://github.com/slack-ruby/slack-api-ref/blob/master/methods/chat/chat.update.json
           def chat_update(options = {})
             throw ArgumentError.new('Required arguments :channel missing') if options[:channel].nil?
+            throw ArgumentError.new('Required arguments :text, :attachments or :blocks missing') if options[:text].nil? && options[:attachments].nil? && options[:blocks].nil?
             throw ArgumentError.new('Required arguments :ts missing') if options[:ts].nil?
             options = options.merge(channel: conversations_id(options)['channel']['id']) if options[:channel]
+            # attachments must be passed as an encoded JSON string
+            if options.key?(:attachments)
+              attachments = options[:attachments]
+              attachments = JSON.dump(attachments) unless attachments.is_a?(String)
+              options = options.merge(attachments: attachments)
+            end
+            # blocks must be passed as an encoded JSON string
+            if options.key?(:blocks)
+              blocks = options[:blocks]
+              blocks = JSON.dump(blocks) unless blocks.is_a?(String)
+              options = options.merge(blocks: blocks)
+            end
             post('chat.update', options)
           end
         end