diff --git a/src/dns.c b/src/dns.c
index 003f8b9cf..1e6f287bb 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -474,9 +474,6 @@ static void dns_session_io_handler(struct appctx *appctx)
 		return;
 	}
 
-
-	ofs = ds->ofs;
-
 	HA_RWLOCK_WRLOCK(DNS_LOCK, &ring->lock);
 	LIST_DEL_INIT(&appctx->wait_entry);
 	HA_RWLOCK_WRUNLOCK(DNS_LOCK, &ring->lock);
@@ -491,10 +488,10 @@ static void dns_session_io_handler(struct appctx *appctx)
 	 * existing messages before grabbing a reference to a location. This
 	 * value cannot be produced after initialization.
 	 */
-	if (unlikely(ofs == ~0)) {
-		ofs = 0;
+	if (unlikely(ds->ofs == ~0)) {
+		ds->ofs = 0;
 
-		HA_ATOMIC_INC(b_peek(buf, ofs));
+		HA_ATOMIC_INC(b_peek(buf, ds->ofs));
 	}
 
 	/* in this loop, ofs always points to the counter byte that precedes
@@ -505,6 +502,10 @@ static void dns_session_io_handler(struct appctx *appctx)
 		/* we were already there, adjust the offset to be relative to
 		 * the buffer's head and remove us from the counter.
 		 */
+		ofs = ds->ofs - b_head_ofs(buf);
+		if (ds->ofs < b_head_ofs(buf))
+			ofs += b_size(buf);
+
 		BUG_ON(ofs >= buf->size);
 		HA_ATOMIC_DEC(b_peek(buf, ofs));
 
@@ -632,7 +633,7 @@ static void dns_session_io_handler(struct appctx *appctx)
 		}
 
 		HA_ATOMIC_INC(b_peek(buf, ofs));
-		ds->ofs = ofs;
+		ds->ofs = b_peek_ofs(buf, ofs);
 	}
 	HA_RWLOCK_RDUNLOCK(DNS_LOCK, &ring->lock);
 
@@ -1108,8 +1109,6 @@ static struct task *dns_process_req(struct task *t, void *context, unsigned int
 	struct dns_session *ds, *ads;
 	HA_SPIN_LOCK(DNS_LOCK, &dss->lock);
 
-	ofs = dss->ofs_req;
-
 	HA_RWLOCK_RDLOCK(DNS_LOCK, &ring->lock);
 
 	/* explanation for the initialization below: it would be better to do
@@ -1120,14 +1119,18 @@ static struct task *dns_process_req(struct task *t, void *context, unsigned int
 	 * existing messages before grabbing a reference to a location. This
 	 * value cannot be produced after initialization.
 	 */
-	if (unlikely(ofs == ~0)) {
-		ofs = 0;
-		HA_ATOMIC_INC(b_peek(buf, ofs));
+	if (unlikely(dss->ofs_req == ~0)) {
+		dss->ofs_req = 0;
+		HA_ATOMIC_INC(b_peek(buf, dss->ofs_req));
 	}
 
 	/* we were already there, adjust the offset to be relative to
 	 * the buffer's head and remove us from the counter.
 	 */
+	ofs = dss->ofs_req - b_head_ofs(buf);
+	if (dss->ofs_req < b_head_ofs(buf))
+		ofs += b_size(buf);
+
 	BUG_ON(ofs >= buf->size);
 	HA_ATOMIC_DEC(b_peek(buf, ofs));
 
@@ -1216,7 +1219,7 @@ static struct task *dns_process_req(struct task *t, void *context, unsigned int
 	}
 
 	HA_ATOMIC_INC(b_peek(buf, ofs));
-	dss->ofs_req = ofs;
+	dss->ofs_req = b_peek_ofs(buf, ofs);
 	HA_RWLOCK_RDUNLOCK(DNS_LOCK, &ring->lock);