diff --git a/.gitignore b/.gitignore
index 3c3629e..2bb2d94 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 node_modules
+index.d.ts
diff --git a/LICENSE b/LICENSE
index f5d8045..3194b3c 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 ISC License
 
-Copyright (c) 2022, Mapbox
+Copyright (c) 2025, Mapbox
 
 Permission to use, copy, modify, and/or distribute this software for any purpose
 with or without fee is hereby granted, provided that the above copyright notice
diff --git a/index.d.ts b/index.d.ts
deleted file mode 100644
index a9d5439..0000000
--- a/index.d.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-export interface PotpackBox {
-  w: number;
-  h: number;
-  /**
-   * X coordinate in the resulting container.
-   */
-  x?: number;
-  /**
-   * Y coordinate in the resulting container.
-   */
-  y?: number;
-}
-
-interface PotpackStats {
-  /**
-   * Width of the resulting container.
-   */
-  w: number;
-  /**
-   * Height of the resulting container.
-   */
-  h: number;
-  /**
-   * The space utilization value (0 to 1). Higher is better.
-   */
-  fill: number;
-}
-
-/**
- * Packs 2D rectangles into a near-square container.
- *
- * Mutates the {@link boxes} array: it's sorted by height,
- * and box objects are augmented with `x`, `y` coordinates.
- */
-declare const potpack: (boxes: PotpackBox[]) => PotpackStats;
-
-export default potpack;
diff --git a/index.js b/index.js
index f117140..b103fad 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,27 @@
-
+/**
+ * @typedef {Object} PotpackBox
+ * @property {number} w Box width.
+ * @property {number} h Box height.
+ * @property {number} [x] X coordinate in the resulting container.
+ * @property {number} [y] Y coordinate in the resulting container.
+ */
+
+/**
+ * @typedef {Object} PotpackStats
+ * @property {number} w Width of the resulting container.
+ * @property {number} h Height of the resulting container.
+ * @property {number} fill The space utilization value (0 to 1). Higher is better.
+ */
+
+/**
+ * Packs 2D rectangles into a near-square container.
+ *
+ * Mutates the {@link boxes} array: it's sorted (by height/width),
+ * and box objects are augmented with `x`, `y` coordinates.
+ *
+ * @param {PotpackBox[]} boxes
+ * @return {PotpackStats}
+ */
 export default function potpack(boxes) {
 
     // calculate total box area and maximum box width
@@ -10,8 +33,8 @@ export default function potpack(boxes) {
         maxWidth = Math.max(maxWidth, box.w);
     }
 
-    // sort the boxes for insertion by height (or width if equal), descending
-    boxes.sort((a, b) => b.h - a.h || b.w - a.w);
+    // sort the boxes for insertion by height, descending
+    boxes.sort((a, b) => b.h - a.h);
 
     // aim for a squarish resulting container,
     // slightly adjusted for sub-100% space utilization
@@ -46,7 +69,7 @@ export default function potpack(boxes) {
             if (box.w === space.w && box.h === space.h) {
                 // space matches the box exactly; remove it
                 const last = spaces.pop();
-                if (i < spaces.length) spaces[i] = last;
+                if (last && i < spaces.length) spaces[i] = last;
 
             } else if (box.h === space.h) {
                 // space matches the box height; update it accordingly
diff --git a/package-lock.json b/package-lock.json
index 1e98dd4..2173305 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,32 +1,36 @@
 {
   "name": "potpack",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "potpack",
-      "version": "2.0.0",
+      "version": "2.1.0",
       "license": "ISC",
       "devDependencies": {
         "@mapbox/shelf-pack": "^3.2.0",
         "bin-pack": "^1.0.2",
-        "eslint": "^9.5.0",
-        "eslint-config-mourner": "^4.0.1"
+        "eslint": "^9.31.0",
+        "eslint-config-mourner": "^4.0.2",
+        "typescript": "^5.8.3"
       }
     },
     "node_modules/@eslint-community/eslint-utils": {
-      "version": "4.4.0",
-      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.4.0.tgz",
-      "integrity": "sha512-1/sA4dwrzBAyeUoQ6oxahHKmrZvsnLCg4RfxW3ZFGGmQkSNQPFNLV9CUEFQP1x9EYXHTo5p6xdhZM1Ne9p/AfA==",
+      "version": "4.7.0",
+      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.7.0.tgz",
+      "integrity": "sha512-dyybb3AcajC7uha6CvhdVRJqaKyn7w2YKqKyAN37NKYgZT36w+iRb0Dymmc5qEJ549c/S31cMMSFd75bteCpCw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "eslint-visitor-keys": "^3.3.0"
+        "eslint-visitor-keys": "^3.4.3"
       },
       "engines": {
         "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
       },
+      "funding": {
+        "url": "https://opencollective.com/eslint"
+      },
       "peerDependencies": {
         "eslint": "^6.0.0 || ^7.0.0 || >=8.0.0"
       }
@@ -45,9 +49,9 @@
       }
     },
     "node_modules/@eslint-community/regexpp": {
-      "version": "4.10.1",
-      "resolved": "https://registry.npmjs.org/@eslint-community/regexpp/-/regexpp-4.10.1.tgz",
-      "integrity": "sha512-Zm2NGpWELsQAD1xsJzGQpYfvICSsFkEpU0jxBjfdC6uNEWXcHnfs9hScFWtXVDVl+rBQJGrl4g1vcKIejpH9dA==",
+      "version": "4.12.1",
+      "resolved": "https://registry.npmjs.org/@eslint-community/regexpp/-/regexpp-4.12.1.tgz",
+      "integrity": "sha512-CCZCDJuduB9OUkFkY2IgppNZMi2lBQgD2qzwXkEia16cge2pijY/aXi96CJMquDMn3nJdlPV1A5KrJEXwfLNzQ==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -55,24 +59,47 @@
       }
     },
     "node_modules/@eslint/config-array": {
-      "version": "0.16.0",
-      "resolved": "https://registry.npmjs.org/@eslint/config-array/-/config-array-0.16.0.tgz",
-      "integrity": "sha512-/jmuSd74i4Czf1XXn7wGRWZCuyaUZ330NH1Bek0Pplatt4Sy1S5haN21SCLLdbeKslQ+S0wEJ+++v5YibSi+Lg==",
+      "version": "0.21.0",
+      "resolved": "https://registry.npmjs.org/@eslint/config-array/-/config-array-0.21.0.tgz",
+      "integrity": "sha512-ENIdc4iLu0d93HeYirvKmrzshzofPw6VkZRKQGe9Nv46ZnWUzcF1xV01dcvEg/1wXUR61OmmlSfyeyO7EvjLxQ==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
-        "@eslint/object-schema": "^2.1.4",
+        "@eslint/object-schema": "^2.1.6",
         "debug": "^4.3.1",
-        "minimatch": "^3.0.5"
+        "minimatch": "^3.1.2"
+      },
+      "engines": {
+        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
+      }
+    },
+    "node_modules/@eslint/config-helpers": {
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/@eslint/config-helpers/-/config-helpers-0.3.0.tgz",
+      "integrity": "sha512-ViuymvFmcJi04qdZeDc2whTHryouGcDlaxPqarTD0ZE10ISpxGUVZGZDx4w01upyIynL3iu6IXH2bS1NhclQMw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
+      }
+    },
+    "node_modules/@eslint/core": {
+      "version": "0.15.1",
+      "resolved": "https://registry.npmjs.org/@eslint/core/-/core-0.15.1.tgz",
+      "integrity": "sha512-bkOp+iumZCCbt1K1CmWf0R9pM5yKpDv+ZXtvSyQpudrI9kuFLp+bM2WOPXImuD/ceQuaa8f5pj93Y7zyECIGNA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@types/json-schema": "^7.0.15"
       },
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
       }
     },
     "node_modules/@eslint/eslintrc": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/@eslint/eslintrc/-/eslintrc-3.1.0.tgz",
-      "integrity": "sha512-4Bfj15dVJdoy3RfZmmo86RK1Fwzn6SstsvK9JS+BaVKqC6QQQQyXekNaC+g+LKNgkQ+2VhGAzm6hO40AhMR3zQ==",
+      "version": "3.3.1",
+      "resolved": "https://registry.npmjs.org/@eslint/eslintrc/-/eslintrc-3.3.1.tgz",
+      "integrity": "sha512-gtF186CXhIl1p4pJNGZw8Yc6RlshoePRvE0X91oPGb3vZ8pM3qOS9W9NGPat9LziaBV7XrJWGylNQXkGcnM3IQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -94,25 +121,80 @@
       }
     },
     "node_modules/@eslint/js": {
-      "version": "9.5.0",
-      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.5.0.tgz",
-      "integrity": "sha512-A7+AOT2ICkodvtsWnxZP4Xxk3NbZ3VMHd8oihydLRGrJgqqdEz1qSeEgXYyT/Cu8h1TWWsQRejIx48mtjZ5y1w==",
+      "version": "9.31.0",
+      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.31.0.tgz",
+      "integrity": "sha512-LOm5OVt7D4qiKCqoiPbA7LWmI+tbw1VbTUowBcUMgQSuM6poJufkFkYDcQpo5KfgD39TnNySV26QjOh7VFpSyw==",
       "dev": true,
       "license": "MIT",
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
+      },
+      "funding": {
+        "url": "https://eslint.org/donate"
       }
     },
     "node_modules/@eslint/object-schema": {
-      "version": "2.1.4",
-      "resolved": "https://registry.npmjs.org/@eslint/object-schema/-/object-schema-2.1.4.tgz",
-      "integrity": "sha512-BsWiH1yFGjXXS2yvrf5LyuoSIIbPrGUWob917o+BTKuZ7qJdxX8aJLRxs1fS9n6r7vESrq1OUqb68dANcFXuQQ==",
+      "version": "2.1.6",
+      "resolved": "https://registry.npmjs.org/@eslint/object-schema/-/object-schema-2.1.6.tgz",
+      "integrity": "sha512-RBMg5FRL0I0gs51M/guSAj5/e14VQ4tpZnQNWwuDT66P14I43ItmPfIZRhO9fUVIPOAQXU47atlywZ/czoqFPA==",
       "dev": true,
       "license": "Apache-2.0",
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
       }
     },
+    "node_modules/@eslint/plugin-kit": {
+      "version": "0.3.3",
+      "resolved": "https://registry.npmjs.org/@eslint/plugin-kit/-/plugin-kit-0.3.3.tgz",
+      "integrity": "sha512-1+WqvgNMhmlAambTvT3KPtCl/Ibr68VldY2XY40SL1CE0ZXiakFR/cbTspaF5HsnpDMvcYYoJHfl4980NBjGag==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@eslint/core": "^0.15.1",
+        "levn": "^0.4.1"
+      },
+      "engines": {
+        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
+      }
+    },
+    "node_modules/@humanfs/core": {
+      "version": "0.19.1",
+      "resolved": "https://registry.npmjs.org/@humanfs/core/-/core-0.19.1.tgz",
+      "integrity": "sha512-5DyQ4+1JEUzejeK1JGICcideyfUbGixgS9jNgex5nqkW+cY7WZhxBigmieN5Qnw9ZosSNVC9KQKyb+GUaGyKUA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=18.18.0"
+      }
+    },
+    "node_modules/@humanfs/node": {
+      "version": "0.16.6",
+      "resolved": "https://registry.npmjs.org/@humanfs/node/-/node-0.16.6.tgz",
+      "integrity": "sha512-YuI2ZHQL78Q5HbhDiBA1X4LmYdXCKCMQIfw0pw7piHJwyREFebJUvrQN4cMssyES6x+vfUbx1CIpaQUKYdQZOw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@humanfs/core": "^0.19.1",
+        "@humanwhocodes/retry": "^0.3.0"
+      },
+      "engines": {
+        "node": ">=18.18.0"
+      }
+    },
+    "node_modules/@humanfs/node/node_modules/@humanwhocodes/retry": {
+      "version": "0.3.1",
+      "resolved": "https://registry.npmjs.org/@humanwhocodes/retry/-/retry-0.3.1.tgz",
+      "integrity": "sha512-JBxkERygn7Bv/GbN5Rv8Ul6LVknS+5Bp6RgDC/O8gEBU/yeH5Ui5C/OlWrTb6qct7LjjfT6Re2NxB0ln0yYybA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=18.18"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/nzakas"
+      }
+    },
     "node_modules/@humanwhocodes/module-importer": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/@humanwhocodes/module-importer/-/module-importer-1.0.1.tgz",
@@ -128,9 +210,9 @@
       }
     },
     "node_modules/@humanwhocodes/retry": {
-      "version": "0.3.0",
-      "resolved": "https://registry.npmjs.org/@humanwhocodes/retry/-/retry-0.3.0.tgz",
-      "integrity": "sha512-d2CGZR2o7fS6sWB7DG/3a95bGKQyHMACZ5aW8qGkkqQpUoZV6C0X7Pc7l4ZNMZkfNBf4VWNe9E1jRsf0G146Ew==",
+      "version": "0.4.3",
+      "resolved": "https://registry.npmjs.org/@humanwhocodes/retry/-/retry-0.4.3.tgz",
+      "integrity": "sha512-bV0Tgo9K4hfPCek+aMAn81RppFKv2ySDQeMoSZuvTASywNTnVJCArCZE2FWqpvIatKu7VMRLWlR1EazvVhDyhQ==",
       "dev": true,
       "license": "Apache-2.0",
       "engines": {
@@ -151,55 +233,15 @@
         "node": ">=6.0.0"
       }
     },
-    "node_modules/@nodelib/fs.scandir": {
-      "version": "2.1.5",
-      "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",
-      "integrity": "sha512-vq24Bq3ym5HEQm2NKCr3yXDwjc7vTsEThRDnkp2DK9p1uqLR+DHurm/NOTo0KG7HYHU7eppKZj3MyqYuMBf62g==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@nodelib/fs.stat": "2.0.5",
-        "run-parallel": "^1.1.9"
-      },
-      "engines": {
-        "node": ">= 8"
-      }
-    },
-    "node_modules/@nodelib/fs.stat": {
-      "version": "2.0.5",
-      "resolved": "https://registry.npmjs.org/@nodelib/fs.stat/-/fs.stat-2.0.5.tgz",
-      "integrity": "sha512-RkhPPp2zrqDAQA/2jNhnztcPAlv64XdhIp7a7454A5ovI7Bukxgt7MX7udwAu3zg1DcpPU0rz3VV1SeaqvY4+A==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">= 8"
-      }
-    },
-    "node_modules/@nodelib/fs.walk": {
-      "version": "1.2.8",
-      "resolved": "https://registry.npmjs.org/@nodelib/fs.walk/-/fs.walk-1.2.8.tgz",
-      "integrity": "sha512-oGB+UxlgWcgQkgwo8GcEGwemoTFt3FIO9ababBmaGwXIoBKZ+GTy0pP185beGg7Llih/NSHSV2XAs1lnznocSg==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@nodelib/fs.scandir": "2.1.5",
-        "fastq": "^1.6.0"
-      },
-      "engines": {
-        "node": ">= 8"
-      }
-    },
     "node_modules/@stylistic/eslint-plugin-js": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin-js/-/eslint-plugin-js-2.3.0.tgz",
-      "integrity": "sha512-lQwoiYb0Fs6Yc5QS3uT8+T9CPKK2Eoxc3H8EnYJgM26v/DgtW+1lvy2WNgyBflU+ThShZaHm3a6CdD9QeKx23w==",
+      "version": "2.13.0",
+      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin-js/-/eslint-plugin-js-2.13.0.tgz",
+      "integrity": "sha512-GPPDK4+fcbsQD58a3abbng2Dx+jBoxM5cnYjBM4T24WFZRZdlNSKvR19TxP8CPevzMOodQ9QVzNeqWvMXzfJRA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@types/eslint": "^8.56.10",
-        "acorn": "^8.11.3",
-        "eslint-visitor-keys": "^4.0.0",
-        "espree": "^10.0.1"
+        "eslint-visitor-keys": "^4.2.0",
+        "espree": "^10.3.0"
       },
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -208,21 +250,10 @@
         "eslint": ">=8.40.0"
       }
     },
-    "node_modules/@types/eslint": {
-      "version": "8.56.10",
-      "resolved": "https://registry.npmjs.org/@types/eslint/-/eslint-8.56.10.tgz",
-      "integrity": "sha512-Shavhk87gCtY2fhXDctcfS3e6FdxWkCx1iUZ9eEUbh7rTqlZT0/IzOkCOVt0fCjcFuZ9FPYfuezTBImfHCDBGQ==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@types/estree": "*",
-        "@types/json-schema": "*"
-      }
-    },
     "node_modules/@types/estree": {
-      "version": "1.0.5",
-      "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.5.tgz",
-      "integrity": "sha512-/kYRxGDLWzHOB7q+wtSUQlFrtcdUccpfy+X+9iMBpHK8QLLhx2wIPYuS5DYtR9Wa/YlZAbIovy7qVdB1Aq6Lyw==",
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.8.tgz",
+      "integrity": "sha512-dWHzHa2WqEXI/O1E9OjrocMTKJl2mSrEolh1Iomrv6U+JuNwaHXsXx9bLu5gG7BUWFIN0skIQJQ/L1rIex4X6w==",
       "dev": true,
       "license": "MIT"
     },
@@ -234,9 +265,9 @@
       "license": "MIT"
     },
     "node_modules/acorn": {
-      "version": "8.12.0",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.12.0.tgz",
-      "integrity": "sha512-RTvkC4w+KNXrM39/lWCUaG0IbRkWdCv7W/IOW9oU6SawyxulvkQy5HQPVTKxEjczcUvapcrw3cFx/60VN/NRNw==",
+      "version": "8.15.0",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
+      "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "dev": true,
       "license": "MIT",
       "bin": {
@@ -273,16 +304,6 @@
         "url": "https://github.com/sponsors/epoberezkin"
       }
     },
-    "node_modules/ansi-regex": {
-      "version": "5.0.1",
-      "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-5.0.1.tgz",
-      "integrity": "sha512-quJQXlTSUGL2LH9SUXo8VwsY4soanhgo6LNSm84E1LBcE8s3O0wpdiRzyR9z/ZZJMlMWv37qOOb9pdJlMUEKFQ==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8"
-      }
-    },
     "node_modules/ansi-styles": {
       "version": "4.3.0",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
@@ -321,9 +342,9 @@
       "license": "MIT"
     },
     "node_modules/brace-expansion": {
-      "version": "1.1.11",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
-      "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
+      "version": "1.1.12",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.12.tgz",
+      "integrity": "sha512-9T9UjW3r0UW5c1Q7GTwllptXwhvYmEzFhzMfZ9H7FQWt+uZePjZPjBP/W1ZEyZ1twGWom5/56TF4lPcqjnDHcg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -386,9 +407,9 @@
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@@ -1001,27 +1025,6 @@
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-      "dev": true,
-      "funding": [
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-          "type": "github",
-          "url": "https://github.com/sponsors/feross"
-        },
-        {
-          "type": "patreon",
-          "url": "https://www.patreon.com/feross"
-        },
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-          "type": "consulting",
-          "url": "https://feross.org/support"
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@@ -1032,41 +1035,6 @@
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-      "dev": true,
-      "funding": [
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-          "type": "github",
-          "url": "https://github.com/sponsors/feross"
-        },
-        {
-          "type": "patreon",
-          "url": "https://www.patreon.com/feross"
-        },
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-          "type": "consulting",
-          "url": "https://feross.org/support"
-        }
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-      "license": "MIT",
-      "dependencies": {
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@@ -1090,19 +1058,6 @@
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@@ -1129,13 +1084,6 @@
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@@ -1149,6 +1097,20 @@
         "node": ">= 0.8.0"
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+      "version": "5.8.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.8.3.tgz",
+      "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
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       "version": "4.4.1",
       "resolved": "https://registry.npmjs.org/uri-js/-/uri-js-4.4.1.tgz",
diff --git a/package.json b/package.json
index a03a83f..26cb2f3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "potpack",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "A tiny library for packing 2D rectangles (for sprite layouts)",
   "main": "index.js",
   "type": "module",
@@ -13,7 +13,8 @@
   ],
   "scripts": {
     "pretest": "eslint *.js",
-    "test": "node test.js"
+    "test": "tsc && node test.js",
+    "prepublishOnly": "npm test"
   },
   "repository": {
     "type": "git",
@@ -35,7 +36,8 @@
   "devDependencies": {
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     "bin-pack": "^1.0.2",
-    "eslint": "^9.5.0",
-    "eslint-config-mourner": "^4.0.1"
+    "eslint": "^9.31.0",
+    "eslint-config-mourner": "^4.0.2",
+    "typescript": "^5.8.3"
   }
 }
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..5a01506
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,15 @@
+{
+    "compilerOptions": {
+        "allowJs": true,
+        "checkJs": true,
+        "strict": true,
+        "emitDeclarationOnly": true,
+        "declaration": true,
+        "target": "es2017",
+        "module": "nodenext",
+        "moduleResolution": "nodenext"
+    },
+    "files": [
+        "index.js"
+    ]
+}