diff --git a/man3/strstr.3 b/man3/strstr.3
index bc9f150a9..8e4ad22bc 100644
--- a/man3/strstr.3
+++ b/man3/strstr.3
@@ -26,8 +26,9 @@
 .\"     386BSD man pages
 .\" Modified Sat Jul 24 17:56:43 1993 by Rik Faith (faith@cs.unc.edu)
 .\" Added history, aeb, 980113.
+.\" 2005-05-05 mtk: added strcasestr()
 .\"
-.TH STRSTR 3  1993-04-12 "GNU" "Linux Programmer's Manual"
+.TH STRSTR 3  2005-04-05 "GNU" "Linux Programmer's Manual"
 .SH NAME
 strstr \- locate a substring
 .SH SYNOPSIS
@@ -35,25 +36,37 @@ strstr \- locate a substring
 .B #include <string.h>
 .sp
 .BI "char *strstr(const char *" haystack ", const char *" needle );
+.sp
+.B #define _GNU_SOURCE
+.sp
+.B #include <string.h>
+.sp
+.BI "char *strcasestr(const char *" haystack ", const char *" needle );
 .fi
 .SH DESCRIPTION
 The \fBstrstr()\fP function finds the first occurrence of the substring
-\fIneedle\fP in the string \fIhaystack\fP.  The terminating `\\0'
+\fIneedle\fP in the string \fIhaystack\fP.  The terminating \`\\0'
 characters are not compared.
+
+The \fBstrcasestr()\fP function is like \fBstrstr()\fP,
+but ignores the case of both arguments.
 .SH "RETURN VALUE"
-The \fBstrstr()\fP function returns a pointer to the beginning of the
+These functions return a pointer to the beginning of the
 substring, or NULL if the substring is not found.
 .SH BUGS
 Early versions of Linux libc (like 4.5.26) would not allow
-an empty argument. Later versions (like 4.6.27) work correctly,
+an empty \fIneedle\fP argument for \fBstrstr()\fP.
+Later versions (like 4.6.27) work correctly,
 and return \fIhaystack\fP when \fIneedle\fP is empty.
 .SH "CONFORMING TO"
-ISO 9899
+The \fBstrstr()\fP function conforms to ISO 9899.
+The \fBstrcasestr()\fP function is a non-standard extension.
 .SH "SEE ALSO"
 .BR index (3),
 .BR memchr (3),
 .BR rindex (3),
 .BR strchr (3),
+.BR strcasecmp (3),
 .BR strpbrk (3),
 .BR strsep (3),
 .BR strspn (3),