diff --git a/src/npf/dpi/dpi.c b/src/npf/dpi/dpi.c
index cd97de9b..f1a61684 100644
--- a/src/npf/dpi/dpi.c
+++ b/src/npf/dpi/dpi.c
@@ -363,7 +363,7 @@ dpi_session_first_packet(struct npf_session *se, struct npf_cache *npc,
 
 free_flows:
 	for (unsigned int j = 0; j < i; j++) {
-		struct flow_procs_tup *tup = &flow->flows[i];
+		struct flow_procs_tup *tup = &flow->flows[j];
 		if (!tup)
 			continue;
 		if (!tup->procs)
diff --git a/src/npf/dpi/ndpi.c b/src/npf/dpi/ndpi.c
index 6959f9b0..8f1bf263 100644
--- a/src/npf/dpi/ndpi.c
+++ b/src/npf/dpi/ndpi.c
@@ -289,7 +289,8 @@ dpi_ndpi_session_flow_destroy(struct dpi_engine_flow *dpi_flow)
 static int
 dpi_ndpi_session_first_packet(struct npf_session *se __unused,
 		struct npf_cache *npc __unused, struct rte_mbuf *mbuf,
-		int dir, uint32_t data_len, struct dpi_engine_flow **dpi_flow)
+		int dir, uint32_t data_len __unused,
+		struct dpi_engine_flow **dpi_flow)
 {
 	struct ndpi_flow *flow = zmalloc_aligned(sizeof(struct ndpi_flow));
 	if (!flow)
@@ -315,8 +316,7 @@ dpi_ndpi_session_first_packet(struct npf_session *se __unused,
 	if (!flow->dest_id)
 		goto dest_id_error;
 
-	if (data_len != 0 && !dpi_ndpi_process_pkt(
-				(struct dpi_engine_flow *)flow, mbuf, dir))
+	if (!dpi_ndpi_process_pkt((struct dpi_engine_flow *)flow, mbuf, dir))
 		return -EINVAL;
 
 	*dpi_flow = (struct dpi_engine_flow *)flow;
diff --git a/src/npf/rproc/npf_ext_appfw.c b/src/npf/rproc/npf_ext_appfw.c
index f94c4af3..eccf73f2 100644
--- a/src/npf/rproc/npf_ext_appfw.c
+++ b/src/npf/rproc/npf_ext_appfw.c
@@ -389,10 +389,15 @@ appfw_action(npf_cache_t *npc, struct rte_mbuf **nbuf, void *arg,
 	 */
 	dpi_flow = npf_session_get_dpi(se);
 	if (!dpi_flow) {
+#ifdef USE_NDPI
 		uint8_t engines[] = { IANA_USER, IANA_NDPI };
-
+		size_t engines_len = 2;
+#else
+		uint8_t engines[] = { IANA_USER };
+		size_t engines_len = 1;
+#endif /* USER_NDPI */
 		rc = dpi_session_first_packet(se, npc, *nbuf,
-				ah->ah_initial_dir, 2, engines);
+				ah->ah_initial_dir, engines_len, engines);
 		if (rc != 0)
 			goto drop;
 		dpi_flow = npf_session_get_dpi(se);
diff --git a/src/npf/rproc/npf_ext_dpi.c b/src/npf/rproc/npf_ext_dpi.c
index dbbae278..7795c776 100644
--- a/src/npf/rproc/npf_ext_dpi.c
+++ b/src/npf/rproc/npf_ext_dpi.c
@@ -178,9 +178,15 @@ dpi_match(npf_cache_t *npc, struct rte_mbuf *mbuf, const struct ifnet *ifp,
 	/* Find or attach the DPI flow info. Do first packet inspection */
 	struct dpi_flow *dpi_flow = npf_session_get_dpi(se);
 	if (!dpi_flow) {
+#ifdef USE_NDPI
 		uint8_t engines[] = {IANA_USER, IANA_NDPI};
+		size_t engines_len = 2;
+#else
+		uint8_t engines[] = {IANA_USER};
+		size_t engines_len = 1;
+#endif /* USER_NDPI */
 		int error = dpi_session_first_packet(se, npc, mbuf,
-				dir, 2, engines);
+				dir, engines_len, engines);
 		if (error)
 			goto drop;
 		dpi_flow = npf_session_get_dpi(se);
diff --git a/src/pipeline/nodes/l3_dpi.c b/src/pipeline/nodes/l3_dpi.c
index 1de631ce..ad078401 100644
--- a/src/pipeline/nodes/l3_dpi.c
+++ b/src/pipeline/nodes/l3_dpi.c
@@ -75,8 +75,15 @@ ip_dpi_process_common(struct pl_packet *pkt, bool v4, int dir)
 	}
 
 	/* Attach the DPI flow info, do first packet inspection */
-	uint8_t engines[] = {IANA_USER, IANA_NDPI};
-	(void)dpi_session_first_packet(se, npc, m, dir, 2, engines);
+#ifdef USE_NDPI
+		uint8_t engines[] = {IANA_USER, IANA_NDPI};
+		size_t engines_len = 2;
+#else
+		uint8_t engines[] = {IANA_USER};
+		size_t engines_len = 1;
+#endif /* USER_NDPI */
+
+	(void)dpi_session_first_packet(se, npc, m, dir, engines_len, engines);
 
 done:
 	if (dir == PFIL_IN)