diff --git a/lib/nodes/influxdb.c b/lib/nodes/influxdb.c
index 315afd608..07d79108a 100644
--- a/lib/nodes/influxdb.c
+++ b/lib/nodes/influxdb.c
@@ -132,7 +132,7 @@ int influxdb_write(struct node *n, struct sample *smps[], unsigned cnt, unsigned
 
 		/* Fields */
 		for (int j = 0; j < smp->length; j++) {
-			struct signal *sig;
+			struct signal *sig = (struct signal *) list_at(smp->signals, j);
 			union signal_data *data = &smp->data[k];
 
 			if (sig->type == SIGNAL_TYPE_AUTO || sig->type == SIGNAL_TYPE_COMPLEX) {