diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 9fbbc01..342085a 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -146,47 +146,40 @@
 	return -EINVAL;
 }
 
-static double get_period_percent(struct hist_entry *he, u64 period)
+double perf_diff__period_percent(struct hist_entry *he, u64 period)
 {
 	u64 total = he->hists->stats.total_period;
 	return (period * 100.0) / total;
 }
 
-double perf_diff__compute_delta(struct hist_entry *he)
+double perf_diff__compute_delta(struct hist_entry *he, struct hist_entry *pair)
 {
-	struct hist_entry *pair = hist_entry__next_pair(he);
-	double new_percent = get_period_percent(he, he->stat.period);
-	double old_percent = pair ? get_period_percent(pair, pair->stat.period) : 0.0;
+	double new_percent = perf_diff__period_percent(he, he->stat.period);
+	double old_percent = perf_diff__period_percent(pair, pair->stat.period);
 
 	he->diff.period_ratio_delta = new_percent - old_percent;
 	he->diff.computed = true;
 	return he->diff.period_ratio_delta;
 }
 
-double perf_diff__compute_ratio(struct hist_entry *he)
+double perf_diff__compute_ratio(struct hist_entry *he, struct hist_entry *pair)
 {
-	struct hist_entry *pair = hist_entry__next_pair(he);
 	double new_period = he->stat.period;
-	double old_period = pair ? pair->stat.period : 0;
+	double old_period = pair->stat.period;
 
 	he->diff.computed = true;
-	he->diff.period_ratio = pair ? (new_period / old_period) : 0;
+	he->diff.period_ratio = new_period / old_period;
 	return he->diff.period_ratio;
 }
 
-s64 perf_diff__compute_wdiff(struct hist_entry *he)
+s64 perf_diff__compute_wdiff(struct hist_entry *he, struct hist_entry *pair)
 {
-	struct hist_entry *pair = hist_entry__next_pair(he);
 	u64 new_period = he->stat.period;
-	u64 old_period = pair ? pair->stat.period : 0;
+	u64 old_period = pair->stat.period;
 
 	he->diff.computed = true;
-
-	if (!pair)
-		he->diff.wdiff = 0;
-	else
-		he->diff.wdiff = new_period * compute_wdiff_w2 -
-				 old_period * compute_wdiff_w1;
+	he->diff.wdiff = new_period * compute_wdiff_w2 -
+			 old_period * compute_wdiff_w1;
 
 	return he->diff.wdiff;
 }
@@ -385,18 +378,21 @@
 
 	while (next != NULL) {
 		struct hist_entry *he = rb_entry(next, struct hist_entry, rb_node);
+		struct hist_entry *pair = hist_entry__next_pair(he);
 
 		next = rb_next(&he->rb_node);
+		if (!pair)
+			continue;
 
 		switch (compute) {
 		case COMPUTE_DELTA:
-			perf_diff__compute_delta(he);
+			perf_diff__compute_delta(he, pair);
 			break;
 		case COMPUTE_RATIO:
-			perf_diff__compute_ratio(he);
+			perf_diff__compute_ratio(he, pair);
 			break;
 		case COMPUTE_WEIGHTED_DIFF:
-			perf_diff__compute_wdiff(he);
+			perf_diff__compute_wdiff(he, pair);
 			break;
 		default:
 			BUG_ON(1);