diff --git a/vsftpd-2.0.5-underscore_uname.patch b/vsftpd-2.0.5-underscore_uname.patch
new file mode 100644
index 0000000..020c6e4
--- /dev/null
+++ b/vsftpd-2.0.5-underscore_uname.patch
@@ -0,0 +1,12 @@
+diff -up vsftpd-2.0.5/sysutil.c.underscore_uname vsftpd-2.0.5/sysutil.c
+--- vsftpd-2.0.5/sysutil.c.underscore_uname	2007-11-30 13:14:50.000000000 +0100
++++ vsftpd-2.0.5/sysutil.c	2007-11-30 13:12:25.000000000 +0100
+@@ -905,7 +905,7 @@ vsf_sysutil_isprint(int the_char)
+ int
+ vsf_sysutil_isalnum(int the_char)
+ {
+-  return isalnum(the_char);
++  return isalnum(the_char) || the_char == '_' || the_char == '.';
+ }
+ 
+ int
diff --git a/vsftpd.spec b/vsftpd.spec
index 7d01a0c..0fef9ad 100644
--- a/vsftpd.spec
+++ b/vsftpd.spec
@@ -45,6 +45,7 @@ Patch30: vsftpd-2.0.5-pam_end.patch
 Patch31: vsftpd-2.0.5-write_race.patch
 Patch32: vsftpd-2.0.5-fix_unique.patch
 Patch33: vsftpd-2.0.5-userlist_log.patch
+Patch34: vsftpd-2.0.5-underscore_uname.patch
 
 BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root
 %if %{tcp_wrappers}
@@ -104,6 +105,7 @@ cp %{SOURCE1} .
 %patch31 -p1 -b .write_race
 %patch32 -p1 -b .fix_unique
 %patch33 -p1 -b .userlist_log
+%patch34 -p1 -b .underscore_uname
 
 %build
 %ifarch s390x
@@ -168,6 +170,7 @@ fi
   (#240550).
 - Fix bad handling of unique files (#392231).
 - Added userlist_log option.
+- Allow usernames to begin with underscore or dot (#339911).
 
 * Thu Nov 08 2007 Martin Nagy <mnagy@redhat.com> - 2.0.5-20
 - Correct calling of pam_end (#235843).