diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
index e4cb28526563..80461c1ae9ef 100644
--- a/include/net/flow_keys.h
+++ b/include/net/flow_keys.h
@@ -2,6 +2,7 @@
 #define _NET_FLOW_KEYS_H
 
 struct flow_keys {
+	/* (src,dst) must be grouped, in the same way than in IP header */
 	__be32 src;
 	__be32 dst;
 	union {
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index f0516d9280c3..0985b9b14b80 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -8,6 +8,16 @@
 #include <linux/ppp_defs.h>
 #include <net/flow_keys.h>
 
+/* copy saddr & daddr, possibly using 64bit load/store
+ * Equivalent to :	flow->src = iph->saddr;
+ *			flow->dst = iph->daddr;
+ */
+static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
+{
+	BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
+		     offsetof(typeof(*flow), src) + sizeof(flow->src));
+	memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
+}
 
 bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
 {
@@ -31,8 +41,7 @@ ip:
 			ip_proto = 0;
 		else
 			ip_proto = iph->protocol;
-		flow->src = iph->saddr;
-		flow->dst = iph->daddr;
+		iph_to_flow_copy_addrs(flow, iph);
 		nhoff += iph->ihl * 4;
 		break;
 	}