diff --git a/src/detectRepeats.ts b/src/detectRepeats.ts
index 0601cc2..e0fa4ac 100644
--- a/src/detectRepeats.ts
+++ b/src/detectRepeats.ts
@@ -1,7 +1,6 @@
 import { eqProps, flatten, zip } from "ramda";
 import { Interval, Comment } from "./ast";
 import { Duration } from "./Duration";
-import { RangeIntensity } from "./Intensity";
 
 export type RepeatedInterval = {
   type: "repeat";
@@ -70,7 +69,7 @@ const extractRepeatedInterval = (intervals: Interval[], i: number): RepeatedInte
   };
 };
 
-const isRangeInterval = (interval: Interval): boolean => interval.intensity instanceof RangeIntensity;
+const isRangeInterval = ({ intensity }: Interval): boolean => intensity.start !== intensity.end;
 
 export const detectRepeats = (intervals: Interval[]): (Interval | RepeatedInterval)[] => {
   if (intervals.length < windowSize) {
diff --git a/src/stats/zoneDistribution.ts b/src/stats/zoneDistribution.ts
index 0d4508b..7b7d2ac 100644
--- a/src/stats/zoneDistribution.ts
+++ b/src/stats/zoneDistribution.ts
@@ -1,6 +1,5 @@
 import { Interval } from "../ast";
 import { Duration } from "../Duration";
-import { RangeIntensity } from "../Intensity";
 import { intensityValueToZoneType, ZoneType } from "../ZoneType";
 import { intervalsToIntensityNumbers } from "./intervalsToIntensityNumbers";
 
@@ -21,12 +20,12 @@ export const zoneDistribution = (intervals: Interval[]): ZoneDuration[] => {
   const zones = emptyZones();
 
   intervals.forEach((interval) => {
-    if (interval.intensity instanceof RangeIntensity) {
+    if (interval.intensity.start === interval.intensity.end) {
+      zones[interval.intensity.zone].duration += interval.duration.seconds;
+    } else {
       intervalsToIntensityNumbers([interval]).forEach((intensityValue) => {
         zones[intensityValueToZoneType(intensityValue)].duration++;
       });
-    } else {
-      zones[interval.intensity.zone].duration += interval.duration.seconds;
     }
   });
 
diff --git a/src/utils/chunkRangeIntervals.ts b/src/utils/chunkRangeIntervals.ts
index 4f2f7a3..db101d4 100644
--- a/src/utils/chunkRangeIntervals.ts
+++ b/src/utils/chunkRangeIntervals.ts
@@ -1,7 +1,7 @@
 import { chain, curry } from "ramda";
 import { Interval } from "../ast";
 import { Duration } from "../Duration";
-import { ConstantIntensity, Intensity, RangeIntensity } from "../Intensity";
+import { ConstantIntensity, Intensity } from "../Intensity";
 
 const chunkDuration = (seconds: number, chunkSize: Duration, intervalDuration: Duration): Duration => {
   return seconds + chunkSize.seconds > intervalDuration.seconds
@@ -26,7 +26,7 @@ const chunkIntensity = (
 };
 
 const chunkInterval = curry((chunkSize: Duration, interval: Interval): Interval[] => {
-  if (!(interval.intensity instanceof RangeIntensity)) {
+  if (interval.intensity.start === interval.intensity.end) {
     return [interval];
   }