diff --git a/428.patch b/428.patch
new file mode 100644
index 0000000..cf3b8bf
--- /dev/null
+++ b/428.patch
@@ -0,0 +1,96 @@
+From 91fb737675bb628ed95094d8310f4e3d76fcd26b Mon Sep 17 00:00:00 2001
+From: Patrick Uiterwijk <patrick@puiterwijk.org>
+Date: Thu, 13 Dec 2018 18:24:53 +0100
+Subject: [PATCH] check_smtp: Add option to prefix PROXY header
+
+This enables checks of SMTP servers that expect the haproxy
+PROXY protocol:  -o smtpd_upstream_proxy_protocol=haproxy.
+
+Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
+---
+ NEWS                 |  1 +
+ plugins/check_smtp.c | 17 ++++++++++++++++-
+ 2 files changed, 17 insertions(+), 1 deletion(-)
+
+diff --git a/NEWS b/NEWS
+index d3b62cd4..fa5333c0 100644
+--- a/NEWS
++++ b/NEWS
+@@ -20,6 +20,7 @@ This file documents the major additions and syntax changes between releases.
+ 	check_radius: Add calling-station-id (cejkar)
+ 	check_swap: Add --no-swap flag (Mario Trangoni)
+ 	ssl_utils: Added certificate expiry data in OK status (check_http, check_smtp, check_tcp) (Matt Capra)
++	check_smtp: Add --proxy flag for PROXY protocol (Patrick Uiterwijk)
+ 
+ 
+ 2.2.2 xxxx-xx-xx
+diff --git a/plugins/check_smtp.c b/plugins/check_smtp.c
+index 33d11803..e05dae01 100644
+--- a/plugins/check_smtp.c
++++ b/plugins/check_smtp.c
+@@ -52,6 +52,7 @@ int days_till_exp_warn, days_till_exp_crit;
+ enum {
+ 	SMTP_PORT	= 25
+ };
++#define PROXY_PREFIX "PROXY TCP4 0.0.0.0 0.0.0.0 25 25\r\n"
+ #define SMTP_EXPECT "220"
+ #define SMTP_HELO "HELO "
+ #define SMTP_EHLO "EHLO "
+@@ -106,6 +107,7 @@ double critical_time = 0;
+ int check_critical_time = FALSE;
+ int verbose = 0;
+ int use_ssl = FALSE;
++short use_proxy_prefix = FALSE;
+ short use_ehlo = FALSE;
+ short use_lhlo = FALSE;
+ short ssl_established = 0;
+@@ -197,6 +199,13 @@ main (int argc, char **argv)
+ 
+ 	if (result == STATE_OK) { /* we connected */
+ 
++		/* If requested, send PROXY header */
++		if (use_proxy_prefix) {
++			if (verbose)
++				printf ("Sending header %s\n", PROXY_PREFIX);
++			send(sd, PROXY_PREFIX, strlen(PROXY_PREFIX), 0);
++		}
++
+ 		/* watch for the SMTP connection string and */
+ 		/* return a WARNING status if we couldn't read any data */
+ 		if (recvlines(buffer, MAX_INPUT_BUFFER) <= 0) {
+@@ -484,6 +493,7 @@ process_arguments (int argc, char **argv)
+ 		{"starttls",no_argument,0,'S'},
+ 		{"certificate",required_argument,0,'D'},
+ 		{"ignore-quit-failure",no_argument,0,'q'},
++		{"proxy",no_argument,0,'r'},
+ 		{0, 0, 0, 0}
+ 	};
+ 
+@@ -500,7 +510,7 @@ process_arguments (int argc, char **argv)
+ 	}
+ 
+ 	while (1) {
+-		c = getopt_long (argc, argv, "+hVv46Lt:p:f:e:c:w:H:C:R:SD:F:A:U:P:q",
++		c = getopt_long (argc, argv, "+hVv46Lrt:p:f:e:c:w:H:C:R:SD:F:A:U:P:q",
+ 		                 longopts, &option);
+ 
+ 		if (c == -1 || c == EOF)
+@@ -617,6 +627,9 @@ process_arguments (int argc, char **argv)
+ #else
+ 			usage (_("SSL support not available - install OpenSSL and recompile"));
+ #endif
++		case 'r':
++			use_proxy_prefix = TRUE;
++			break;
+ 		case 'S':
+ 		/* starttls */
+ 			use_ssl = TRUE;
+@@ -820,6 +833,8 @@ print_help (void)
+   printf ("    %s\n", _("FROM-address to include in MAIL command, required by Exchange 2000")),
+   printf (" %s\n", "-F, --fqdn=STRING");
+   printf ("    %s\n", _("FQDN used for HELO"));
++  printf (" %s\n", "-r, --proxy-prefix");
++  printf ("    %s\n", _("Use PROXY protocol prefix for the connection."));
+ #ifdef HAVE_SSL
+   printf (" %s\n", "-D, --certificate=INTEGER[,INTEGER]");
+   printf ("    %s\n", _("Minimum number of days a certificate has to be valid."));
diff --git a/nagios-plugins.spec b/nagios-plugins.spec
index 88967e4..869d028 100644
--- a/nagios-plugins.spec
+++ b/nagios-plugins.spec
@@ -5,7 +5,7 @@
 
 Name: nagios-plugins
 Version: 2.2.1
-Release: 14.20180725git3429dad%{?dist}
+Release: 15.20180725git3429dad%{?dist}
 Summary: Host/service/network monitoring program plugins for Nagios
 
 Group: Applications/System
@@ -21,6 +21,8 @@ Patch7: nagios-plugins-0007-Fix-the-use-lib-statement-and-the-external-ntp-comma
 Patch10: nagios-plugins-0010-include-mysql-version-header.patch
 Patch11: nagios-plugins-0011-fix-perl-shebang.patch
 
+Patch100: https://patch-diff.githubusercontent.com/raw/nagios-plugins/nagios-plugins/pull/428.patch
+
 BuildRequires: %{_bindir}/mailq
 BuildRequires: %{_bindir}/ps
 BuildRequires: %{_bindir}/ssh
@@ -605,6 +607,7 @@ Provides check_wave support for Nagios.
 #%if 0%{?fedora} >27 || 0%{?rhel} > 7
 %patch11 -p1 -b .fix_perl_shebang
 #%endif
+%patch100 -p1 -b .check_smtp_proxy
 
 %build
 
@@ -853,6 +856,9 @@ chmod 644 %{buildroot}/%{_libdir}/nagios/plugins/utils.pm
 %{_libdir}/nagios/plugins/check_wave
 
 %changelog
+* Thu Dec 13 2018 Patrick Uiterwijk <puiterwijk@puiterwijk.org> - 2.2.1-15.20180725git3429dad
+- Add upstream PR #428 to add PROXY protocol support to check_smtp
+
 * Wed Jul 25 2018 Stephen Smoogen <smooge@fedoraproject.org> - 2.2.1-14.20180725git3429dad
 - Update to latest git and fix release string to match
 - Fix BZ#1604915