diff --git a/lib/msun/man/cos.3 b/lib/msun/man/cos.3
index 87a0b6cddc76..90e0ee4066cc 100644
--- a/lib/msun/man/cos.3
+++ b/lib/msun/man/cos.3
@@ -83,6 +83,6 @@ These functions conform to
 .St -isoC-99 .
 .Sh HISTORY
 The
-.Fn sin
+.Fn cos
 function first appeared in
 .At v1 .