diff --git a/doc/bird.sgml b/doc/bird.sgml
index 300a71f3..fab49105 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1940,6 +1940,7 @@ protocol ospf <name> {
 				nonbroadcast|nbma|pointomultipoint|ptmp];
 			strict nonbroadcast <switch>;
 			real broadcast <switch>;
+			ptp netmask <switch>;
 			check link <switch>;
 			ecmp weight <num>;
 			authentication [none|simple|cryptographic];
@@ -2183,6 +2184,18 @@ protocol ospf <name> {
 	 probably is not interoperable with other OSPF
 	 implementations. Default value is no.
 
+	<tag>ptp netmask <m/switch/</tag>
+	 In <cf/type ptp/ network configurations, OSPFv2
+	 implementations should ignore received netmask field in hello
+	 packets and should send hello packets with zero netmask field
+	 on unnumbered PtP links. But some OSPFv2 implementations
+	 perform netmask checking even for PtP links. This option
+	 specifies whether real netmask will be used in hello packets
+	 on <cf/type ptp/ interfaces. You should ignore this option
+	 unless you meet some compatibility problems related to this
+	 issue. Default value is no for unnumbered PtP links, yes
+	 otherwise.
+
 	<tag>check link <M>switch</M></tag>
 	 If set, a hardware link state (reported by OS) is taken into
 	 consideration. When a link disappears (e.g. an ethernet cable is
diff --git a/proto/ospf/config.Y b/proto/ospf/config.Y
index 3325a5de..2f1ee624 100644
--- a/proto/ospf/config.Y
+++ b/proto/ospf/config.Y
@@ -116,7 +116,7 @@ CF_KEYWORDS(NONE, SIMPLE, AUTHENTICATION, STRICT, CRYPTOGRAPHIC)
 CF_KEYWORDS(ELIGIBLE, POLL, NETWORKS, HIDDEN, VIRTUAL, CHECK, LINK)
 CF_KEYWORDS(RX, BUFFER, LARGE, NORMAL, STUBNET, HIDDEN, SUMMARY, TAG, EXTERNAL)
 CF_KEYWORDS(WAIT, DELAY, LSADB, ECMP, LIMIT, WEIGHT, NSSA, TRANSLATOR, STABILITY)
-CF_KEYWORDS(GLOBAL, LSID, ROUTER, SELF, INSTANCE, REAL)
+CF_KEYWORDS(GLOBAL, LSID, ROUTER, SELF, INSTANCE, REAL, NETMASK)
 
 %type <t> opttext
 %type <ld> lsadb_args
@@ -280,6 +280,7 @@ ospf_iface_item:
  | TYPE POINTOMULTIPOINT { OSPF_PATT->type = OSPF_IT_PTMP ; }
  | TYPE PTMP { OSPF_PATT->type = OSPF_IT_PTMP ; }
  | REAL BROADCAST bool { OSPF_PATT->real_bcast = $3; if (!ospf_cfg_is_v2()) cf_error("Real broadcast option requires OSPFv2"); }
+ | PTP NETMASK bool { OSPF_PATT->ptp_netmask = $3; if (!ospf_cfg_is_v2()) cf_error("Real netmask option requires OSPFv2"); }
  | TRANSMIT DELAY expr { OSPF_PATT->inftransdelay = $3 ; if (($3<=0) || ($3>65535)) cf_error("Transmit delay must be in range 1-65535"); }
  | PRIORITY expr { OSPF_PATT->priority = $2 ; if (($2<0) || ($2>255)) cf_error("Priority must be in range 0-255"); }
  | STRICT NONBROADCAST bool { OSPF_PATT->strictnbma = $3 ; }
@@ -354,6 +355,7 @@ ospf_iface_start:
   OSPF_PATT->type = OSPF_IT_UNDEF;
   init_list(&OSPF_PATT->nbma_list);
   OSPF_PATT->autype = OSPF_AUTH_NONE;
+  OSPF_PATT->ptp_netmask = 2; /* not specified */
   reset_passwords();
  }
 ;
diff --git a/proto/ospf/hello.c b/proto/ospf/hello.c
index c2518708..8f2e497f 100644
--- a/proto/ospf/hello.c
+++ b/proto/ospf/hello.c
@@ -267,7 +267,8 @@ ospf_hello_send(struct ospf_iface *ifa, int kind, struct ospf_neighbor *dirn)
 
     ps->netmask = htonl(u32_mkmask(ifa->addr->pxlen));
 
-    if ((ifa->type == OSPF_IT_VLINK) || (ifa->type == OSPF_IT_PTP))
+    if ((ifa->type == OSPF_IT_VLINK) ||
+	((ifa->type == OSPF_IT_PTP) && !ifa->ptp_netmask))
       ps->netmask = 0;
 
     ps->helloint = ntohs(ifa->helloint);
diff --git a/proto/ospf/iface.c b/proto/ospf/iface.c
index 8613ec85..19f4c585 100644
--- a/proto/ospf/iface.c
+++ b/proto/ospf/iface.c
@@ -538,6 +538,10 @@ ospf_iface_new(struct ospf_area *oa, struct ifa *addr, struct ospf_iface_patt *i
   ifa->passwords = ip->passwords;
   ifa->instance_id = ip->instance_id;
 
+  ifa->ptp_netmask = !(addr->flags & IA_PEER);
+  if (ip->ptp_netmask < 2)
+    ifa->ptp_netmask = ip->ptp_netmask;
+
   ifa->type = ospf_iface_classify(ip->type, addr);
 
   /* Check validity of interface type */
diff --git a/proto/ospf/ospf.h b/proto/ospf/ospf.h
index 146d07f6..1c411a71 100644
--- a/proto/ospf/ospf.h
+++ b/proto/ospf/ospf.h
@@ -246,6 +246,7 @@ struct ospf_iface
   u16 rxbuf;			/* Buffer size */
   u8 check_link;		/* Whether iface link change is used */
   u8 ecmp_weight;		/* Weight used for ECMP */
+  u8 ptp_netmask;		/* Send real netmask for P2P */
 };
 
 struct ospf_md5
@@ -749,8 +750,9 @@ struct ospf_iface_patt
   u8 check_link;
   u8 ecmp_weight;
   u8 real_bcast;		/* Not really used in OSPFv3 */
-  list *passwords;
+  u8 ptp_netmask;		/* bool but 2 for unspecified */
   u8 instance_id;
+  list *passwords;
 };
 
 int ospf_import_control(struct proto *p, rte **new, ea_list **attrs,