diff --git a/ractor.rb b/ractor.rb
index 953d3ceddc..8e229d4700 100644
--- a/ractor.rb
+++ b/ractor.rb
@@ -1,4 +1,4 @@
-# Ractor is a Actor-model abstraction for Ruby that provides thread-safe parallel execution.
+# Ractor is an Actor-model abstraction for Ruby that provides thread-safe parallel execution.
 #
 # Ractor.new can make a new Ractor, and it will run in parallel.
 #