diff --git a/libnetutil/netutil.cc b/libnetutil/netutil.cc
index 7c78bf3fa..482d11118 100644
--- a/libnetutil/netutil.cc
+++ b/libnetutil/netutil.cc
@@ -730,8 +730,7 @@ static const void *ip_get_data_primitive(const void *packet, unsigned int *len,
     memcpy(&sin6->sin6_addr, &ip6->ip6_dst, IP6_ADDR_LEN);
 
     hdr->ttl = ip6->ip6_hlim;
-    /* abstract_hdr.ipid is limited to 16 bits. */
-    hdr->ipid = (u16) ntohl(ip6->ip6_flow & IP6_FLOWLABEL_MASK);
+    hdr->ipid = ntohl(ip6->ip6_flow & IP6_FLOWLABEL_MASK);
     return ipv6_get_data_primitive(ip6, len, &hdr->proto, upperlayer_only);
   }
 
diff --git a/libnetutil/netutil.h b/libnetutil/netutil.h
index 70ca665e0..0cf798736 100644
--- a/libnetutil/netutil.h
+++ b/libnetutil/netutil.h
@@ -160,7 +160,7 @@ struct abstract_ip_hdr {
   struct sockaddr_storage dst;
   u8 proto; /* IPv4 proto or IPv6 next header. */
   u8 ttl;   /* IPv4 TTL or IPv6 hop limit. */
-  u16 ipid;  /* IPv4 IP ID or IPv6 flow label. */
+  u32 ipid; /* IPv4 IP ID or IPv6 flow label. */
 };
 
 void netutil_fatal(const char *str, ...)
diff --git a/scan_engine.cc b/scan_engine.cc
index 7e3bea98c..b89d69f64 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -269,7 +269,7 @@ struct IPExtraProbeData_sctp {
 };
 
 struct IPExtraProbeData {
-  u16 ipid; /* host byte order */
+  u32 ipid; /* host byte order */
   union {
     struct IPExtraProbeData_icmp icmp;
     struct IPExtraProbeData_tcp tcp;
@@ -328,7 +328,7 @@ public:
     }
     /* not reached */
   }
-  u16 ipid() const {
+  u32 ipid() const {
     return probes.IP.ipid;
   }
   u16 icmpid() const; // ICMP ident if protocol is ICMP
@@ -934,7 +934,7 @@ void UltraProbe::setIP(u8 *ippacket, u32 len, const probespec *pspec) {
     data = ipv6_get_data_any(ip6, &len, &hdr);
     assert(data != NULL);
     assert(len == (u32) ntohs(ip6->ip6_plen));
-    probes.IP.ipid = ntohl(ip6->ip6_flow & IP6_FLOWLABEL_MASK) & 0xFFFF;
+    probes.IP.ipid = ntohl(ip6->ip6_flow & IP6_FLOWLABEL_MASK);
     hdr = ip6->ip6_nxt;
   } else {
     fatal("Bogus packet passed to %s -- only IP packets allowed", __func__);