diff --git a/src/isc-dhcp/patch/0013-Fix-dhcrelay-agent-option-buffer-pointer-logic.patch b/src/isc-dhcp/patch/0013-Fix-dhcrelay-agent-option-buffer-pointer-logic.patch
new file mode 100644
index 0000000000..051b58966c
--- /dev/null
+++ b/src/isc-dhcp/patch/0013-Fix-dhcrelay-agent-option-buffer-pointer-logic.patch
@@ -0,0 +1,53 @@
+From 0a2f9a62bceb90b0d30461add2e25c4ce7a24547 Mon Sep 17 00:00:00 2001
+From: Thomas Markwalder <tmark@isc.org>
+Date: Fri, 20 Dec 2019 10:11:54 -0500
+Subject: [PATCH] [#71] Fix dhcrelay agent option buffer pointer logic
+
+relay/dhcrelay.c
+    strip_relay_agent_options()
+    strip_relay_agent_options()
+    - corrected buffer pointer logic
+
+---
+ relay/dhcrelay.c | 18 ++++++++++++++----
+ 1 file changed, 14 insertions(+), 4 deletions(-)
+
+diff --git a/relay/dhcrelay.c b/relay/dhcrelay.c
+index 896e1e2e..980dacae 100644
+--- a/relay/dhcrelay.c
++++ b/relay/dhcrelay.c
+@@ -1238,8 +1238,13 @@ strip_relay_agent_options(struct interface_info *in,
+ 				return (0);
+ 
+ 			if (sp != op) {
+-				memmove(sp, op, op[1] + 2);
+-				sp += op[1] + 2;
++				size_t mlen = op[1] + 2;
++				memmove(sp, op, mlen);
++				sp += mlen;
++				if (sp > max) {
++					return (0);
++				}
++
+ 				op = nextop;
+ 			} else
+ 				op = sp = nextop;
+@@ -1620,8 +1620,13 @@ add_relay_agent_options(struct interface_info *ip, struct dhcp_packet *packet,
+ 			end_pad = NULL;
+ 
+ 			if (sp != op) {
+-				memmove(sp, op, op[1] + 2);
+-				sp += op[1] + 2;
++				size_t mlen = op[1] + 2;
++				memmove(sp, op, mlen);
++				sp += mlen;
++				if (sp > max) {
++					return (0);
++				}
++
+ 				op = nextop;
+ 			} else
+ 				op = sp = nextop;
+-- 
+2.17.1
+
diff --git a/src/isc-dhcp/patch/series b/src/isc-dhcp/patch/series
index 5397aa0c6e..b9efee0192 100644
--- a/src/isc-dhcp/patch/series
+++ b/src/isc-dhcp/patch/series
@@ -11,3 +11,4 @@
 0010-Bugfix-correctly-set-interface-netmask.patch
 0011-dhcp-relay-Prevent-Buffer-Overrun.patch
 0012-add-option-si-to-support-using-src-intf-ip-in-relay.patch
+0013-Fix-dhcrelay-agent-option-buffer-pointer-logic.patch