diff --git a/man3/strstr.3 b/man3/strstr.3
index 62268e5c6..9ee249013 100644
--- a/man3/strstr.3
+++ b/man3/strstr.3
@@ -78,9 +78,9 @@ T{
 T}	Thread safety	MT-Safe locale
 .TE
 .SH CONFORMING TO
-The
-.BR strstr ()
-function conforms to C89 and C99.
+.BR strstr ():
+POSIX.1-2001, POSIX.1-2008, C89, C99.
+
 The
 .BR strcasestr ()
 function is a nonstandard extension.