diff --git a/clock.c b/clock.c
index fc44089..af49d7b 100644
--- a/clock.c
+++ b/clock.c
@@ -210,9 +210,10 @@ UInteger8 clock_class(struct clock *c)
 }
 
 struct clock *clock_create(int phc_index, struct interface *iface, int count,
-			   struct defaultDS *ds, struct port_defaults *pod)
+			   enum timestamp_type timestamping, struct defaultDS *ds,
+			   struct port_defaults *pod)
 {
-	int i, max_adj, sw_ts = 0;
+	int i, max_adj, sw_ts = timestamping == TS_SOFTWARE ? 1 : 0;
 	struct clock *c = &the_clock;
 	char phc[32];
 
@@ -238,13 +239,6 @@ struct clock *clock_create(int phc_index, struct interface *iface, int count,
 		max_adj = 512000;
 	}
 
-	for (i = 0; i < count; i++) {
-		if (iface[i].timestamping == TS_SOFTWARE) {
-			sw_ts = 1;
-			break;
-		}
-	}
-
 	c->servo = servo_create("pi", max_adj, sw_ts);
 	if (!c->servo) {
 		pr_err("Failed to create clock servo");
@@ -274,7 +268,7 @@ struct clock *clock_create(int phc_index, struct interface *iface, int count,
 
 	for (i = 0; i < count; i++) {
 		c->port[i] = port_open(pod, phc_index, iface[i].name, iface[i].transport,
-				       iface[i].timestamping, 1+i, iface[i].dm, c);
+				       timestamping, 1+i, iface[i].dm, c);
 		if (!c->port[i]) {
 			pr_err("failed to open port %s", iface[i].name);
 			return NULL;
diff --git a/clock.h b/clock.h
index e48aaeb..ddf5889 100644
--- a/clock.h
+++ b/clock.h
@@ -35,7 +35,6 @@ struct interface {
 	char *name;
 	enum delay_mechanism dm;
 	enum transport_type transport;
-	enum timestamp_type timestamping;
 };
 
 /** Opaque type. */
@@ -68,16 +67,18 @@ UInteger8 clock_class(struct clock *c);
  * Create a clock instance. There can only be one clock in any system,
  * so subsequent calls will destroy the previous clock instance.
  *
- * @param phc_index   PTP hardware clock device to use.
- *                    Pass -1 to select CLOCK_REALTIME.
- * @param interface   An array of network interfaces.
- * @param count       The number of elements in @a interfaces.
- * @param ds          A pointer to a default data set for the clock.
- * @param pod         A pointer to a default port data set for the clock.
- * @return            A pointer to the single global clock instance.
+ * @param phc_index    PTP hardware clock device to use.
+ *                     Pass -1 to select CLOCK_REALTIME.
+ * @param interface    An array of network interfaces.
+ * @param count        The number of elements in @a interfaces.
+ * @param timestamping The timestamping mode for this clock.
+ * @param ds           A pointer to a default data set for the clock.
+ * @param pod          A pointer to a default port data set for the clock.
+ * @return             A pointer to the single global clock instance.
  */
 struct clock *clock_create(int phc_index, struct interface *iface, int count,
-			   struct defaultDS *ds, struct port_defaults *pod);
+			   enum timestamp_type timestamping, struct defaultDS *ds,
+			   struct port_defaults *pod);
 
 /**
  * Obtains a clock's default data set.
diff --git a/ptp4l.c b/ptp4l.c
index 14d93f2..95400cc 100644
--- a/ptp4l.c
+++ b/ptp4l.c
@@ -73,7 +73,7 @@ static void usage(char *progname)
 int main(int argc, char *argv[])
 {
 	char *config = NULL, *req_phc = NULL, *progname;
-	int c, i, nports = 0, slaveonly = 0;
+	int c, nports = 0, slaveonly = 0;
 	struct interface iface[MAX_PORTS];
 	enum delay_mechanism dm = DM_E2E;
 	enum transport_type transport = TRANS_UDP_IPV4;
@@ -159,9 +159,6 @@ int main(int argc, char *argv[])
 		usage(progname);
 		return -1;
 	}
-	for (i = 0; i < nports; i++) {
-		iface[i].timestamping = timestamping;
-	}
 
 	/* determine PHC Clock index */
 	if (timestamping == TS_SOFTWARE || timestamping == TS_LEGACY_HW) {
@@ -222,7 +219,7 @@ int main(int argc, char *argv[])
 		ds.clockQuality.clockClass = 255;
 	}
 
-	clock = clock_create(phc_index, iface, nports, &ds, &pod);
+	clock = clock_create(phc_index, iface, nports, timestamping, &ds, &pod);
 	if (!clock) {
 		fprintf(stderr, "failed to create a clock\n");
 		return -1;