diff --git a/lib/Glib.js b/lib/Glib.js
index 1b50e87..0248048 100644
--- a/lib/Glib.js
+++ b/lib/Glib.js
@@ -89,7 +89,7 @@ class Glib {
   flatMap(mapFn) {
     return new Glib(
       (function*(iterable) {
-        let index = 0;
+        let index = 0n;
         for (const entry of iterable) {
           yield* mapFn(entry, index++);
         }
@@ -330,7 +330,7 @@ class Glib {
     );
   }
   reduceScoreK(chooseFn) {
-    return this.reduce((a, b) => (chooseFn(a[1] > b[1]) ? a : b))[0];
+    return this.reduce((a, b) => (chooseFn(a[1], b[1]) ? a : b))[0];
   }
   minScoreK() {
     return this.reduceScoreK((a, b) => a < b);
@@ -338,6 +338,15 @@ class Glib {
   maxScoreK() {
     return this.reduceScoreK((a, b) => a > b);
   }
+  reduceScore(chooseFn) {
+    return this.reduce((a, b) => (chooseFn(a[1], b[1]) ? a : b));
+  }
+  minScore() {
+    return this.reduceScore((a, b) => a < b);
+  }
+  maxScoreK() {
+    return this.reduceScore((a, b) => a > b);
+  }
 }
 
 module.exports = Glib;
diff --git a/lib/_pollute/array.js b/lib/_pollute/array.js
index d28f430..87aa824 100644
--- a/lib/_pollute/array.js
+++ b/lib/_pollute/array.js
@@ -16,6 +16,14 @@ Object.defineProperty(Array.prototype, 'set', {
   },
 });
 
+Object.defineProperty(Array.prototype, 'lengthN', {
+  enumerable: false,
+  configurable: false,
+  get() {
+    return BigInt(this.length);
+  },
+});
+
 Array.prototype.safeSplice = function safeSplice(...args) {
   const spliced = this.slice();
   spliced.splice(...args);
diff --git a/lib/_pollute/string.js b/lib/_pollute/string.js
index b0f9b63..c88596d 100644
--- a/lib/_pollute/string.js
+++ b/lib/_pollute/string.js
@@ -1,5 +1,13 @@
 const crypto = require('crypto');
 
+Object.defineProperty(String.prototype, 'lengthN', {
+  enumerable: false,
+  configurable: false,
+  get() {
+    return BigInt(this.length);
+  },
+});
+
 Object.defineProperty(String.prototype, 'md5', {
   enumerable: false,
   configurable: false,
diff --git a/solutions/2017/1.js b/solutions/2017/1.js
index c2932cc..3c2bbbf 100644
--- a/solutions/2017/1.js
+++ b/solutions/2017/1.js
@@ -8,14 +8,14 @@ const VALUE = {
 module.exports = {
   '1': (input) =>
     Glib.fromIterable(input)
-      .filter((char, index) => char === input[(index + 1) % input.length])
+      .filter((char, index) => char === input[(index + 1n) % input.lengthN])
       .toInts()
       .sum(),
   '2': (input) =>
     Glib.fromIterable(input)
       .filter(
         (char, index) =>
-          char === input[(index + input.length / 2) % input.length],
+          char === input[(index + input.lengthN / 2n) % input.lengthN],
       )
       .toInts()
       .sum(),
diff --git a/solutions/2019/3.js b/solutions/2019/3.js
index 33b6885..6512b3e 100644
--- a/solutions/2019/3.js
+++ b/solutions/2019/3.js
@@ -23,7 +23,7 @@ module.exports = {
         ...Glib.fromLines(input).map((line) =>
           twodee
             .everyStep(parseLine(line))
-            .map((pt, i) => [pt.string, i + 1])
+            .map((pt, i) => [pt.string, i + 1n])
             .toMap(),
         ),
       ),