diff --git a/main.c b/main.c
index 4613c96..83d00aa 100644
--- a/main.c
+++ b/main.c
@@ -339,10 +339,18 @@ static void output_summary(void)
 
 	if (INFO_GTE(STATS, 1)) {
 		rprintf(FCLIENT, "\n");
-		rprintf(FINFO,
-			"sent %s bytes  received %s bytes  %s bytes/sec\n",
-			human_num(total_written), human_num(total_read),
-			human_dnum((total_written + total_read)/(0.5 + (endtime - starttime)), 2));
+		/** time() may have returned -1 so only indicate bytes/sec
+		 * if it could be calculated */
+		if ((starttime != -1) && (endtime != -1)) {
+			rprintf(FINFO,
+				"sent %s bytes  received %s bytes  %s bytes/sec\n",
+				human_num(total_written), human_num(total_read),
+				human_dnum((total_written + total_read)/(0.5 + (endtime - starttime)), 2));
+		} else {
+			rprintf(FINFO,
+				"sent %s bytes  received %s bytes  unknown bytes/sec\n",
+				human_num(total_written), human_num(total_read));
+		}
 		rprintf(FINFO, "total size is %s  speedup is %s%s\n",
 			human_num(stats.total_size),
 			comma_dnum((double)stats.total_size / (total_written+total_read), 2),