diff --git a/lib/core/project_config/index.ts b/lib/core/project_config/index.ts
index a58c9cdc2..07b206df6 100644
--- a/lib/core/project_config/index.ts
+++ b/lib/core/project_config/index.ts
@@ -32,6 +32,7 @@ import {
   VariableType,
   VariationVariable,
   Integration,
+  FeatureVariableValue,
 } from '../../shared_types';
 
 interface TryCreatingProjectConfigConfig {
@@ -692,8 +693,8 @@ export const getTypeCastValue = function(
   variableValue: string,
   variableType: VariableType,
   logger: LogHandler
-): unknown {
-  let castValue;
+): FeatureVariableValue {
+  let castValue : FeatureVariableValue;
 
   switch (variableType) {
     case FEATURE_VARIABLE_TYPES.BOOLEAN:
diff --git a/lib/export_types.ts b/lib/export_types.ts
index cfd498591..759bb86c0 100644
--- a/lib/export_types.ts
+++ b/lib/export_types.ts
@@ -22,6 +22,7 @@ export {
   UserAttributeValue,
   UserAttributes,
   OptimizelyConfig,
+  FeatureVariableValue,
   OptimizelyVariable,
   OptimizelyVariation,
   OptimizelyExperiment,
diff --git a/lib/optimizely/index.ts b/lib/optimizely/index.ts
index c2b26478e..a7c6c29fe 100644
--- a/lib/optimizely/index.ts
+++ b/lib/optimizely/index.ts
@@ -35,6 +35,7 @@ import {
   FeatureVariable,
   OptimizelyOptions,
   OptimizelyDecideOption,
+  FeatureVariableValue,
   OptimizelyDecision,
   Client,
 } from '../shared_types';
@@ -777,7 +778,7 @@ export default class Optimizely implements Client {
    *                                                type, or null if the feature key is invalid or
    *                                                the variable key is invalid
    */
-  getFeatureVariable(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): unknown {
+  getFeatureVariable(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): FeatureVariableValue {
     try {
       if (!this.isValidInstance()) {
         this.logger.log(LOG_LEVEL.ERROR, LOG_MESSAGES.INVALID_OBJECT, MODULE_NAME, 'getFeatureVariable');
@@ -819,7 +820,7 @@ export default class Optimizely implements Client {
     variableType: string | null,
     userId: string,
     attributes?: UserAttributes
-  ): unknown {
+  ): FeatureVariableValue {
     if (!this.validateInputs({ feature_key: featureKey, variable_key: variableKey, user_id: userId }, attributes)) {
       return null;
     }
@@ -911,7 +912,7 @@ export default class Optimizely implements Client {
     variation: Variation | null,
     variable: FeatureVariable,
     userId: string
-  ): unknown {
+  ): FeatureVariableValue {
     const configObj = this.projectConfigManager.getConfig();
     if (!configObj) {
       return null;
diff --git a/lib/shared_types.ts b/lib/shared_types.ts
index 5caf705f9..f156eaee4 100644
--- a/lib/shared_types.ts
+++ b/lib/shared_types.ts
@@ -311,6 +311,8 @@ export interface OptimizelyExperiment {
   };
 }
 
+export type FeatureVariableValue = number | string | boolean | object | null;
+
 export interface OptimizelyVariable {
   id: string;
   key: string;
@@ -330,7 +332,7 @@ export interface Client {
   getForcedVariation(experimentKey: string, userId: string): string | null;
   isFeatureEnabled(featureKey: string, userId: string, attributes?: UserAttributes): boolean;
   getEnabledFeatures(userId: string, attributes?: UserAttributes): string[];
-  getFeatureVariable(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): unknown;
+  getFeatureVariable(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): FeatureVariableValue;
   getFeatureVariableBoolean(
     featureKey: string,
     variableKey: string,