diff --git a/flow.c b/flow.c
index da71fe1..91c0046 100644
--- a/flow.c
+++ b/flow.c
@@ -152,12 +152,10 @@ static void flow_set_state(struct flow_common *f, enum flow_state state)
  * flow_set_type() - Set type and move to TYPED
  * @flow:	Flow to change state
  * @type:	Type for new flow
- * @iniside:	Which side initiated the new flow
  *
  * Return: @flow
  */
-union flow *flow_set_type(union flow *flow, enum flow_type type,
-			  unsigned iniside)
+union flow *flow_set_type(union flow *flow, enum flow_type type)
 {
 	struct flow_common *f = &flow->f;
 
@@ -165,7 +163,6 @@ union flow *flow_set_type(union flow *flow, enum flow_type type,
 	ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_NEW);
 	ASSERT(f->type == FLOW_TYPE_NONE);
 
-	(void)iniside;
 	f->type = type;
 	flow_set_state(f, FLOW_STATE_TYPED);
 	return flow;
diff --git a/flow.h b/flow.h
index e61d35e..9530938 100644
--- a/flow.h
+++ b/flow.h
@@ -100,6 +100,11 @@ extern const uint8_t flow_proto[];
 #define FLOW_PROTO(f)				\
 	((f)->type < FLOW_NUM_TYPES ? flow_proto[(f)->type] : 0)
 
+#define SIDES			2
+
+#define INISIDE			0	/* Initiating side */
+#define TGTSIDE			1	/* Target side */
+
 /**
  * struct flow_common - Common fields for packet flows
  * @state:	State of the flow table entry
diff --git a/flow_table.h b/flow_table.h
index 17b9ea7..28e36b9 100644
--- a/flow_table.h
+++ b/flow_table.h
@@ -107,10 +107,8 @@ static inline flow_sidx_t flow_sidx(const struct flow_common *f,
 union flow *flow_alloc(void);
 void flow_alloc_cancel(union flow *flow);
 
-union flow *flow_set_type(union flow *flow, enum flow_type type,
-			  unsigned iniside);
-#define FLOW_SET_TYPE(flow_, t_, var_, i_)	\
-	(&flow_set_type((flow_), (t_), (i_))->var_)
+union flow *flow_set_type(union flow *flow, enum flow_type type);
+#define FLOW_SET_TYPE(flow_, t_, var_)	(&flow_set_type((flow_), (t_))->var_)
 
 void flow_activate(struct flow_common *f);
 #define FLOW_ACTIVATE(flow_)			\
diff --git a/icmp.c b/icmp.c
index fc72955..3567ad7 100644
--- a/icmp.c
+++ b/icmp.c
@@ -45,10 +45,6 @@
 #define ICMP_ECHO_TIMEOUT	60 /* s, timeout for ICMP socket activity */
 #define ICMP_NUM_IDS		(1U << 16)
 
-/* Sides of a flow as we use them for ping streams */
-#define	SOCKSIDE	0
-#define	TAPSIDE		1
-
 #define PINGF(idx)		(&(FLOW(idx)->ping))
 
 /* Indexed by ICMP echo identifier */
@@ -167,7 +163,7 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 	if (!flow)
 		return NULL;
 
-	pingf = FLOW_SET_TYPE(flow, flowtype, ping, TAPSIDE);
+	pingf = FLOW_SET_TYPE(flow, flowtype, ping);
 
 	pingf->seq = -1;
 	pingf->id = id;
@@ -180,7 +176,7 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 		bind_if = c->ip6.ifname_out;
 	}
 
-	ref.flowside = FLOW_SIDX(flow, SOCKSIDE);
+	ref.flowside = FLOW_SIDX(flow, TGTSIDE);
 	pingf->sock = sock_l4(c, af, flow_proto[flowtype], bind_addr, bind_if,
 			      0, ref.data);
 
diff --git a/tcp.c b/tcp.c
index 398bda7..a15b6f5 100644
--- a/tcp.c
+++ b/tcp.c
@@ -303,10 +303,6 @@
 
 #include "flow_table.h"
 
-/* Sides of a flow as we use them in "tap" connections */
-#define	SOCKSIDE	0
-#define	TAPSIDE		1
-
 #define TCP_FRAMES_MEM			128
 #define TCP_FRAMES							\
 	(c->mode == MODE_PASST ? TCP_FRAMES_MEM : 1)
@@ -581,7 +577,7 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
 	union epoll_ref ref = { .type = EPOLL_TYPE_TCP, .fd = conn->sock,
-				.flowside = FLOW_SIDX(conn, SOCKSIDE) };
+				.flowside = FLOW_SIDX(conn, !conn->tapside), };
 	struct epoll_event ev = { .data.u64 = ref.u64 };
 
 	if (conn->events == CLOSED) {
@@ -1134,7 +1130,7 @@ static uint64_t tcp_conn_hash(const struct ctx *c,
 static inline unsigned tcp_hash_probe(const struct ctx *c,
 				      const struct tcp_tap_conn *conn)
 {
-	flow_sidx_t sidx = FLOW_SIDX(conn, TAPSIDE);
+	flow_sidx_t sidx = FLOW_SIDX(conn, conn->tapside);
 	unsigned b = tcp_conn_hash(c, conn) % TCP_HASH_TABLE_SIZE;
 
 	/* Linear probing */
@@ -1154,7 +1150,7 @@ static void tcp_hash_insert(const struct ctx *c, struct tcp_tap_conn *conn)
 {
 	unsigned b = tcp_hash_probe(c, conn);
 
-	tc_hash[b] = FLOW_SIDX(conn, TAPSIDE);
+	tc_hash[b] = FLOW_SIDX(conn, conn->tapside);
 	flow_dbg(conn, "hash table insert: sock %i, bucket: %u", conn->sock, b);
 }
 
@@ -2004,7 +2000,8 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
 			goto cancel;
 	}
 
-	conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp, TAPSIDE);
+	conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
+	conn->tapside = INISIDE;
 	conn->sock = s;
 	conn->timer = -1;
 	conn_event(c, conn, TAP_SYN_RCVD);
@@ -2716,9 +2713,9 @@ static void tcp_tap_conn_from_sock(struct ctx *c, in_port_t dstport,
 				   const union sockaddr_inany *sa,
 				   const struct timespec *now)
 {
-	struct tcp_tap_conn *conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp,
-						  SOCKSIDE);
+	struct tcp_tap_conn *conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
 
+	conn->tapside = TGTSIDE;
 	conn->sock = s;
 	conn->timer = -1;
 	conn->ws_to_tap = conn->ws_from_tap = 0;
@@ -2870,7 +2867,7 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events)
 	struct tcp_tap_conn *conn = CONN(ref.flowside.flow);
 
 	ASSERT(conn->f.type == FLOW_TCP);
-	ASSERT(ref.flowside.side == SOCKSIDE);
+	ASSERT(ref.flowside.side == !conn->tapside);
 
 	if (conn->events == CLOSED)
 		return;
diff --git a/tcp_conn.h b/tcp_conn.h
index 52bd815..e8c51c3 100644
--- a/tcp_conn.h
+++ b/tcp_conn.h
@@ -13,6 +13,7 @@
  * struct tcp_tap_conn - Descriptor for a TCP connection (not spliced)
  * @f:			Generic flow information
  * @in_epoll:		Is the connection in the epoll set?
+ * @tapside:		Which side of the flow faces the tap/guest interface
  * @tap_mss:		MSS advertised by tap/guest, rounded to 2 ^ TCP_MSS_BITS
  * @sock:		Socket descriptor number
  * @events:		Connection events, implying connection states
@@ -39,6 +40,7 @@ struct tcp_tap_conn {
 	struct flow_common f;
 
 	bool		in_epoll	:1;
+	unsigned	tapside		:1;
 
 #define TCP_RETRANS_BITS		3
 	unsigned int	retrans		:TCP_RETRANS_BITS;
@@ -106,7 +108,6 @@ struct tcp_tap_conn {
 	uint32_t	seq_init_from_tap;
 };
 
-#define SIDES			2
 /**
  * struct tcp_splice_conn - Descriptor for a spliced TCP connection
  * @f:			Generic flow information
diff --git a/tcp_splice.c b/tcp_splice.c
index 852a93b..31e2173 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -471,7 +471,7 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 		return false;
 	}
 
-	conn = FLOW_SET_TYPE(flow, FLOW_TCP_SPLICE, tcp_splice, 0);
+	conn = FLOW_SET_TYPE(flow, FLOW_TCP_SPLICE, tcp_splice);
 
 	conn->flags = af == AF_INET ? 0 : SPLICE_V6;
 	conn->s[0] = s0;