diff --git a/package.json b/package.json
index b4f5dd1..c3ad2e6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk-common",
-  "version": "4.13.0",
+  "version": "4.13.1",
   "description": "Common library for Eppo JavaScript SDKs (web, react native, and node)",
   "main": "dist/index.js",
   "files": [
diff --git a/src/client/eppo-client.spec.ts b/src/client/eppo-client.spec.ts
index fad2c13..a761d8d 100644
--- a/src/client/eppo-client.spec.ts
+++ b/src/client/eppo-client.spec.ts
@@ -79,6 +79,7 @@ describe('EppoClient E2E test', () => {
   const mockFlag: Flag = {
     key: flagKey,
     enabled: true,
+    entityId: 123,
     variationType: VariationType.STRING,
     variations: { a: variationA, b: variationB },
     allocations: [
@@ -195,6 +196,16 @@ describe('EppoClient E2E test', () => {
       client.setAssignmentLogger(mockLogger);
       expect(td.explain(mockLogger.logAssignment).callCount).toEqual(MAX_EVENT_QUEUE_SIZE);
     });
+
+    it('should log assignment event with entityId', () => {
+      const mockLogger = td.object<IAssignmentLogger>();
+      const client = new EppoClient({ flagConfigurationStore: storage });
+      client.setAssignmentLogger(mockLogger);
+      client.getStringAssignment(flagKey, 'subject-to-be-logged', {}, 'default-value');
+      expect(td.explain(mockLogger.logAssignment).callCount).toEqual(1);
+      const loggedAssignmentEvent = td.explain(mockLogger.logAssignment).calls[0].args[0];
+      expect(loggedAssignmentEvent.entityId).toEqual(123);
+    });
   });
 
   describe('check type match', () => {
diff --git a/src/client/eppo-client.ts b/src/client/eppo-client.ts
index 3b47ece..ec37f01 100644
--- a/src/client/eppo-client.ts
+++ b/src/client/eppo-client.ts
@@ -1287,7 +1287,7 @@ export default class EppoClient {
     });
   }
 
-  private maybeLogAssignment(result: FlagEvaluation & { entityId?: number }) {
+  private maybeLogAssignment(result: FlagEvaluation) {
     const {
       flagKey,
       format,
diff --git a/src/client/eppo-precomputed-client.ts b/src/client/eppo-precomputed-client.ts
index 7db1436..49a4ff6 100644
--- a/src/client/eppo-precomputed-client.ts
+++ b/src/client/eppo-precomputed-client.ts
@@ -237,6 +237,7 @@ export default class EppoPrecomputedClient {
       allocationKey: precomputedFlag.allocationKey ?? '',
       extraLogging: precomputedFlag.extraLogging ?? {},
       doLog: precomputedFlag.doLog,
+      entityId: null,
     };
 
     try {
diff --git a/src/evaluator.ts b/src/evaluator.ts
index ded3132..98ab3fd 100644
--- a/src/evaluator.ts
+++ b/src/evaluator.ts
@@ -30,6 +30,7 @@ export interface FlagEvaluationWithoutDetails {
   extraLogging: Record<string, string>;
   // whether to log assignment event
   doLog: boolean;
+  entityId: number | null;
 }
 
 export interface FlagEvaluation extends FlagEvaluationWithoutDetails {
@@ -122,6 +123,7 @@ export class Evaluator {
                 extraLogging: split.extraLogging ?? {},
                 doLog: allocation.doLog,
                 flagEvaluationDetails,
+                entityId: flag.entityId ?? null,
               };
             }
           }
@@ -227,6 +229,7 @@ export function noneResult(
     extraLogging: {},
     doLog: false,
     flagEvaluationDetails,
+    entityId: null,
   };
 }
 
@@ -288,5 +291,6 @@ export function overrideResult(
     format: '',
     allocationKey: overrideAllocationKey,
     extraLogging: {},
+    entityId: null,
   };
 }