diff --git a/src/bin/helpers.ts b/src/bin/helpers.ts
index c108189..859ac05 100644
--- a/src/bin/helpers.ts
+++ b/src/bin/helpers.ts
@@ -9,6 +9,7 @@ import {
   SUPPORTED_DATA_FORMATS,
   SUPPORTED_FORMATS,
 } from '@bin/constants.js'
+import { DoubleOf } from '@common/types.js'
 
 export const getPackageVersion = async () => {
   try {
@@ -78,7 +79,7 @@ const sliceBuffer = (buffer: string | Buffer, start?: number, end?: number) => {
   }
 }
 
-export const evenAndRemainder = (divisor: number, n: number): [number, number] => {
+export const evenAndRemainder = (divisor: number, n: number): DoubleOf<number> => {
   return [Math.floor(n / divisor), n % divisor]
 }
 
diff --git a/src/common/types.ts b/src/common/types.ts
index 17e2e29..d75182f 100644
--- a/src/common/types.ts
+++ b/src/common/types.ts
@@ -26,6 +26,8 @@ export type ArxQuaternion = {
   w: number
 }
 
+export type DoubleOf<T> = [T, T]
+
 export type TripleOf<T> = [T, T, T]
 
 export type QuadrupleOf<T> = [T, T, T, T]
diff --git a/src/fts/helpers.ts b/src/fts/helpers.ts
index c204c4c..ac7bb9d 100644
--- a/src/fts/helpers.ts
+++ b/src/fts/helpers.ts
@@ -1,5 +1,5 @@
 import { any } from '@common/helpers.js'
-import { QuadrupleOf, TripleOf } from '@common/types.js'
+import { DoubleOf, QuadrupleOf, TripleOf } from '@common/types.js'
 import { ArxPolygon, ArxPolygonFlags } from '@fts/Polygon.js'
 import { ArxVertex } from '@fts/Vertex.js'
 import { COORDS_THAT_ROUND_UP } from '@fts/constants.js'
@@ -31,7 +31,7 @@ const doCoordsNeedToBeRoundedUp = (coords: TripleOf<number>) => {
   return any(([x, y, z]) => a === x && b === y && c === z, COORDS_THAT_ROUND_UP)
 }
 
-export const getCellCoords = ([a, b, c]: QuadrupleOf<ArxVertex>): [number, number] => {
+export const getCellCoords = ([a, b, c]: QuadrupleOf<ArxVertex>): DoubleOf<number> => {
   const x = (a.x + b.x + c.x) / 3
   const z = (a.z + b.z + c.z) / 3
 
diff --git a/src/utils.ts b/src/utils.ts
index f69f5ff..d6346f9 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,5 +1,5 @@
 export { getCellCoords } from '@fts/helpers.js'
 
-export type { TripleOf, QuadrupleOf, Optional, Expand, RecursiveExpand } from '@common/types.js'
+export type { DoubleOf, TripleOf, QuadrupleOf, Optional, Expand, RecursiveExpand } from '@common/types.js'
 
 export { MAP_WIDTH_IN_CELLS, MAP_DEPTH_IN_CELLS } from '@common/constants.js'