diff --git a/include/ruby/internal/stdalign.h b/include/ruby/internal/stdalign.h
index ff90f2f0d1..b9a24d31a3 100644
--- a/include/ruby/internal/stdalign.h
+++ b/include/ruby/internal/stdalign.h
@@ -116,7 +116,7 @@ struct rbimpl_alignof {
 #  * querying the alignment of a type,  you definitely should use that instead.
 #  * There are 2 known pitfalls for this fallback implementation:
 #  *
-#  * Fitst, it is either an undefined  behaviour (C) or an explicit error (C++)
+#  * First, it is either an undefined  behaviour (C) or an explicit error (C++)
 #  * to define a  struct inside of `offsetof`. C compilers  tend to accept such
 #  * things, but AFAIK C++ has no room to allow.
 #  *