diff --git a/lib/skyfall/firehose/account_message.rb b/lib/skyfall/firehose/account_message.rb
index e63a8dc..df52bf9 100644
--- a/lib/skyfall/firehose/account_message.rb
+++ b/lib/skyfall/firehose/account_message.rb
@@ -24,7 +24,7 @@ module Skyfall
     #
     def initialize(type_object, data_object)
       super
-      check_if_not_nil :seq, :did, :time, :active
+      check_if_not_nil %w(seq did time active)
 
       @active = @data_object['active']
       @status = @data_object['status']&.to_sym
diff --git a/lib/skyfall/firehose/commit_message.rb b/lib/skyfall/firehose/commit_message.rb
index 9eca292..a4c1849 100644
--- a/lib/skyfall/firehose/commit_message.rb
+++ b/lib/skyfall/firehose/commit_message.rb
@@ -26,7 +26,7 @@ module Skyfall
     #
     def initialize(type_object, data_object)
       super
-      check_if_not_nil :seq, :repo, :commit, :blocks, :ops, :time
+      check_if_not_nil %w(seq repo commit blocks ops time)
     end
 
     # @return [CID] CID (Content Identifier) of the commit
diff --git a/lib/skyfall/firehose/identity_message.rb b/lib/skyfall/firehose/identity_message.rb
index 6bafcdd..1f47a76 100644
--- a/lib/skyfall/firehose/identity_message.rb
+++ b/lib/skyfall/firehose/identity_message.rb
@@ -26,7 +26,7 @@ module Skyfall
     #
     def initialize(type_object, data_object)
       super
-      check_if_not_nil :seq, :did, :time
+      check_if_not_nil %w(seq did time)
 
       @handle = @data_object['handle']
     end
diff --git a/lib/skyfall/firehose/info_message.rb b/lib/skyfall/firehose/info_message.rb
index 3f59673..692f13a 100644
--- a/lib/skyfall/firehose/info_message.rb
+++ b/lib/skyfall/firehose/info_message.rb
@@ -37,7 +37,7 @@ module Skyfall
     #
     def initialize(type_object, data_object)
       super
-      check_if_not_nil :name
+      check_if_not_nil %w(name)
 
       @name = @data_object['name']
       @message = @data_object['message']
diff --git a/lib/skyfall/firehose/labels_message.rb b/lib/skyfall/firehose/labels_message.rb
index 9c5bf74..dd3a23d 100644
--- a/lib/skyfall/firehose/labels_message.rb
+++ b/lib/skyfall/firehose/labels_message.rb
@@ -26,7 +26,7 @@ module Skyfall
     #
     def initialize(type_object, data_object)
       super
-      check_if_not_nil :seq, :labels
+      check_if_not_nil %w(seq labels)
 
       @labels = @data_object['labels'].map { |x| Label.new(x) }
     end
diff --git a/lib/skyfall/firehose/message.rb b/lib/skyfall/firehose/message.rb
index d1459ba..a55871a 100644
--- a/lib/skyfall/firehose/message.rb
+++ b/lib/skyfall/firehose/message.rb
@@ -145,10 +145,10 @@ module Skyfall
     end
 
     # Checks if all required fields are set in the data object.
-    # @param fields [Array<Symbol, String>] list of fields to check
+    # @param fields [Array<String>] list of fields to check
     # @raise [DecodeError] if any of the fields is nil or not set
-    def check_if_not_nil(*fields)
-      missing = fields.select { |f| @data_object[f.to_s].nil? }
+    def check_if_not_nil(fields)
+      missing = fields.select { |f| @data_object[f].nil? }
 
       raise DecodeError.new("Missing event details (#{missing.map(&:to_s).join(', ')})") if missing.length > 0
     end