diff --git a/include/osmocom/netif/osmux.h b/include/osmocom/netif/osmux.h
index dd89973..f52fcb4 100644
--- a/include/osmocom/netif/osmux.h
+++ b/include/osmocom/netif/osmux.h
@@ -47,10 +47,12 @@ struct osmux_in_handle {
 	char *data;				/* internal data */
 };
 
+#define OSMUX_MAX_CONCURRENT_CALLS	8
+
 /* one per OSmux circuit_id, ie. one per RTP flow. */
 struct osmux_out_handle {
-	uint16_t rtp_seq[8];
-	uint32_t rtp_timestamp[8];
+	uint16_t rtp_seq[OSMUX_MAX_CONCURRENT_CALLS];
+	uint32_t rtp_timestamp[OSMUX_MAX_CONCURRENT_CALLS];
 };
 
 static inline uint8_t *osmux_get_payload(struct osmux_hdr *osmuxh)
diff --git a/src/osmux.c b/src/osmux.c
index ad18c36..5916edc 100644
--- a/src/osmux.c
+++ b/src/osmux.c
@@ -385,7 +385,7 @@ void osmux_xfrm_input_init(struct osmux_in_handle *h)
 	batch->timer.cb = osmux_batch_timer_expired;
 	batch->timer.data = h;
 
-	for (i=0; i<8; i++)
+	for (i=0; i<OSMUX_MAX_CONCURRENT_CALLS; i++)
 		batch->ccid[i] = -1;
 
 	h->data = (void *)batch;
@@ -475,7 +475,7 @@ void osmux_xfrm_input_register_ccid(struct osmux_in_handle *h, uint32_t ssrc)
 	struct osmux_batch *batch = (struct osmux_batch *)h->data;;
 	int i, found = 0;
 
-	for (i=0; i<8; i++) {
+	for (i=0; i<OSMUX_MAX_CONCURRENT_CALLS; i++) {
 		if (batch->ccid[i] == ssrc)
 			continue;
 		if (batch->ccid[i] < 0) {
@@ -498,7 +498,7 @@ int osmux_xfrm_input_get_ccid(struct osmux_in_handle *h, uint32_t ssrc)
 	struct osmux_batch *batch = (struct osmux_batch *)h->data;;
 	int i, found = 0;
 
-	for (i=0; i<8; i++) {
+	for (i=0; i<OSMUX_MAX_CONCURRENT_CALLS; i++) {
 		if (batch->ccid[i] == ssrc) {
 			found = 1;
 			break;
@@ -512,7 +512,7 @@ void osmux_xfrm_output_init(struct osmux_out_handle *h)
 {
 	int i;
 
-	for (i=0; i<8; i++) {
+	for (i=0; i<OSMUX_MAX_CONCURRENT_CALLS; i++) {
 		h->rtp_seq[i] = (uint16_t)random();
 		h->rtp_timestamp[i] = (uint32_t)random();
 	}