diff --git a/ospfd/ospf_opaque.h b/ospfd/ospf_opaque.h
index 7d401c3dcc..aeaeea9189 100644
--- a/ospfd/ospf_opaque.h
+++ b/ospfd/ospf_opaque.h
@@ -77,6 +77,8 @@
 
 #define OPAQUE_TYPE_RANGE_RESERVED(type) (127 < (type) && (type) <= 255)
 
+#define OSPF_OPAQUE_LSA_MIN_SIZE 4U
+
 #define VALID_OPAQUE_INFO_LEN(lsahdr)                                          \
 	((ntohs((lsahdr)->length) >= sizeof(struct lsa_header))                \
 	 && ((ntohs((lsahdr)->length) < OSPF_MAX_LSA_SIZE))                    \
diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 1efdfee3b4..7c32c18d4c 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -108,9 +108,9 @@ static const uint16_t ospf_lsa_minlen[] = {
 	0,
 	OSPF_AS_EXTERNAL_LSA_MIN_SIZE,
 	0,
-	0,
-	0,
-	0,
+	OSPF_OPAQUE_LSA_MIN_SIZE,
+	OSPF_OPAQUE_LSA_MIN_SIZE,
+	OSPF_OPAQUE_LSA_MIN_SIZE,
 };
 
 /* for ospf_check_auth() */