diff --git a/lib/libc/stdlib/getsubopt.3 b/lib/libc/stdlib/getsubopt.3
index 801c27e694c..1688426da08 100644
--- a/lib/libc/stdlib/getsubopt.3
+++ b/lib/libc/stdlib/getsubopt.3
@@ -41,7 +41,7 @@
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
-.In unistd.h
+.In stdlib.h
 .Vt extern char *suboptarg ;
 .Ft int
 .Fn getsubopt "char **optionp" "char * const *tokens" "char **valuep"