diff --git a/package-lock.json b/package-lock.json
index 3f55635f72..604a7fb1b1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5651,7 +5651,8 @@
     "long": {
       "version": "5.2.3",
       "resolved": "https://registry.npmjs.org/long/-/long-5.2.3.tgz",
-      "integrity": "sha512-lcHwpNoggQTObv5apGNCTdJrO69eHOZMi4BNC+rTLER8iHAqGrUVeLh/irVIM7zTw2bOXA8T6uNPeujwOLg/2Q=="
+      "integrity": "sha512-lcHwpNoggQTObv5apGNCTdJrO69eHOZMi4BNC+rTLER8iHAqGrUVeLh/irVIM7zTw2bOXA8T6uNPeujwOLg/2Q==",
+      "optional": true
     },
     "loupe": {
       "version": "2.3.7",
diff --git a/package.json b/package.json
index 6a68c36302..a31cc77ae3 100644
--- a/package.json
+++ b/package.json
@@ -203,7 +203,6 @@
     "farmhash-modern": "^1.1.0",
     "jsonwebtoken": "^9.0.0",
     "jwks-rsa": "^3.1.0",
-    "long": "^5.2.3",
     "node-forge": "^1.3.1",
     "uuid": "^10.0.0"
   },
diff --git a/src/remote-config/condition-evaluator-internal.ts b/src/remote-config/condition-evaluator-internal.ts
index 46803f8402..2be55ec08d 100644
--- a/src/remote-config/condition-evaluator-internal.ts
+++ b/src/remote-config/condition-evaluator-internal.ts
@@ -26,7 +26,6 @@ import {
   PercentConditionOperator
 } from './remote-config-api';
 import * as farmhash from 'farmhash-modern';
-import long = require('long');
 
 /**
  * Encapsulates condition evaluation logic to simplify organization and
@@ -147,26 +146,18 @@ export class ConditionEvaluator {
     const seedPrefix = seed && seed.length > 0 ? `${seed}.` : '';
     const stringToHash = `${seedPrefix}${context.randomizationId}`;
 
+    const hash64 = ConditionEvaluator.hashSeededRandomizationId(stringToHash)
 
-    // Using a 64-bit long for consistency with the Remote Config fetch endpoint.
-    let hash64 = long.fromString(farmhash.fingerprint64(stringToHash).toString());
+    const instanceMicroPercentile = hash64 % BigInt(100 * 1_000_000);
 
-    // Negate the hash if its value is less than 0. We handle this manually because the
-    // Long library doesn't provided an absolute value method.
-    if (hash64.lt(0)) {
-      hash64 = hash64.negate();
-    }
-
-    const instanceMicroPercentile = hash64.mod(100 * 1_000_000);
-    
     switch (percentOperator) {
     case PercentConditionOperator.LESS_OR_EQUAL:
-      return instanceMicroPercentile.lte(normalizedMicroPercent);
+      return instanceMicroPercentile <= normalizedMicroPercent;
     case PercentConditionOperator.GREATER_THAN:
-      return instanceMicroPercentile.gt(normalizedMicroPercent);
+      return instanceMicroPercentile > normalizedMicroPercent;
     case PercentConditionOperator.BETWEEN:
-      return instanceMicroPercentile.gt(normalizedMicroPercentLowerBound)
-        && instanceMicroPercentile.lte(normalizedMicroPercentUpperBound);
+      return instanceMicroPercentile > normalizedMicroPercentLowerBound
+          && instanceMicroPercentile <= normalizedMicroPercentUpperBound;
     case PercentConditionOperator.UNKNOWN:
     default:
       break;
@@ -175,4 +166,20 @@ export class ConditionEvaluator {
     // TODO: add logging once we have a wrapped logger.
     return false;
   }
+
+  // Visible for testing
+  static hashSeededRandomizationId(seededRandomizationId: string): bigint {
+    // For consistency with the Remote Config fetch endpoint's percent condition behavior
+    // we use Farmhash's fingerprint64 algorithm and interpret the resulting unsigned value
+    // as a signed value.
+    let hash64 = BigInt.asIntN(64, farmhash.fingerprint64(seededRandomizationId));
+
+    // Manually negate the hash if its value is less than 0, since Math.abs doesn't
+    // support BigInt.
+    if (hash64 < 0) {
+      hash64 = -hash64;
+    }
+
+    return hash64;
+  }
 }
diff --git a/test/unit/remote-config/condition-evaluator.spec.ts b/test/unit/remote-config/condition-evaluator.spec.ts
index 5bb0f89133..17e524f6d8 100644
--- a/test/unit/remote-config/condition-evaluator.spec.ts
+++ b/test/unit/remote-config/condition-evaluator.spec.ts
@@ -858,4 +858,77 @@ describe('ConditionEvaluator', () => {
       }
     });
   });
+
+  describe('hashSeededRandomizationId', () => {
+    // The Farmhash algorithm produces a 64 bit unsigned integer,
+    // which we convert to a signed integer for legacy compatibility.
+    // This has caused confusion in the past, so we explicitly
+    // test here.
+    it('should leave numbers <= 2^63-1 (max signed long) as is', function () {
+      if (nodeVersion.startsWith('14')) {
+        this.skip();
+      }
+      
+      const stub = sinon
+        .stub(farmhash, 'fingerprint64')
+        // 2^63-1 = 9223372036854775807.
+        .returns(BigInt('9223372036854775807'));
+      stubs.push(stub);
+
+      const actual = ConditionEvaluator.hashSeededRandomizationId('anything');
+      
+      expect(actual).to.equal(BigInt('9223372036854775807'))
+    });
+
+    it('should convert 2^63 to negative (min signed long) and then find the absolute value', function () {
+      if (nodeVersion.startsWith('14')) {
+        this.skip();
+      }
+      
+      const stub = sinon
+        .stub(farmhash, 'fingerprint64')
+        // 2^63 = 9223372036854775808.
+        .returns(BigInt('9223372036854775808'));
+      stubs.push(stub);
+
+      const actual = ConditionEvaluator.hashSeededRandomizationId('anything');
+      
+      // 2^63 is the negation of 2^63-1
+      expect(actual).to.equal(BigInt('9223372036854775808'))
+    });
+
+    it('should convert 2^63+1 to negative and then find the absolute value', function () {
+      if (nodeVersion.startsWith('14')) {
+        this.skip();
+      }
+      
+      const stub = sinon
+        .stub(farmhash, 'fingerprint64')
+        // 2^63+1 9223372036854775809.
+        .returns(BigInt('9223372036854775809'));
+      stubs.push(stub);
+
+      const actual = ConditionEvaluator.hashSeededRandomizationId('anything');
+      
+      // 2^63+1 is larger than 2^63, so the absolute value is smaller
+      expect(actual).to.equal(BigInt('9223372036854775807'))
+    });
+
+    it('should handle the value that initially caused confusion', function () {
+      if (nodeVersion.startsWith('14')) {
+        this.skip();
+      }
+      
+      const stub = sinon
+        .stub(farmhash, 'fingerprint64')
+        // We were initially confused about the nature of this value ...
+        .returns(BigInt('16081085603393958147'));
+      stubs.push(stub);
+
+      const actual = ConditionEvaluator.hashSeededRandomizationId('anything');
+      
+      // ... Now we know it's the unsigned equivalent of this absolute value.
+      expect(actual).to.equal(BigInt('2365658470315593469'))
+    });
+  });
 });