diff --git a/src/isc-dhcp/patch/0012-Don-t-skip-down-interfaces-when-discovering-interfac.patch b/src/isc-dhcp/patch/0012-Don-t-skip-down-interfaces-when-discovering-interfac.patch
new file mode 100644
index 0000000000..f088b035ed
--- /dev/null
+++ b/src/isc-dhcp/patch/0012-Don-t-skip-down-interfaces-when-discovering-interfac.patch
@@ -0,0 +1,32 @@
+From 06850e9beb2c50b5cc23fc94168acd9ae58d8ef8 Mon Sep 17 00:00:00 2001
+From: Joe LeVeque <jolevequ@microsoft.com>
+Date: Fri, 6 Dec 2019 05:53:09 +0000
+Subject: [PATCH] Don't skip down interfaces when discovering interfaces in
+ relay mode
+
+When discovering interfaces in relay mode, don't skip interfaces just
+because they're down. If we fail to discover the interfaces because they
+are down when the relay starts, but then are brought up at a later point
+in time, the relay will discard any packets received on them because it
+didn't discover the interface(s) when it started up.
+---
+ common/discover.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/common/discover.c b/common/discover.c
+index 8d5b958..5efff49 100644
+--- a/common/discover.c
++++ b/common/discover.c
+@@ -1016,7 +1016,8 @@ discover_interfaces(int state) {
+ 		      info.flags & IFF_LOOPBACK ||
+ 		      info.flags & IFF_POINTOPOINT) && !tmp) ||
+ 		    (!(info.flags & IFF_UP) &&
+-		     state != DISCOVER_UNCONFIGURED))
++		     state != DISCOVER_UNCONFIGURED &&
++		     state != DISCOVER_RELAY))
+ 			continue;
+ 		
+ 		/* If there isn't already an interface by this name,
+-- 
+2.17.1
+
diff --git a/src/isc-dhcp/patch/series b/src/isc-dhcp/patch/series
index 1b83f2166b..ec68967e28 100644
--- a/src/isc-dhcp/patch/series
+++ b/src/isc-dhcp/patch/series
@@ -10,3 +10,4 @@
 0009-CVE-2018-5733.patch
 0010-CVE-2018-5732.patch
 0008-interface-name-maxlen-crash.patch
+0012-Don-t-skip-down-interfaces-when-discovering-interfac.patch