diff --git a/Sources/Confidence/FlagEvaluation.swift b/Sources/Confidence/FlagEvaluation.swift
index 1193f4b4..393fbc2a 100644
--- a/Sources/Confidence/FlagEvaluation.swift
+++ b/Sources/Confidence/FlagEvaluation.swift
@@ -13,6 +13,7 @@ public enum ErrorCode {
     case invalidContext
     case flagNotFound
     case evaluationError
+    case typeMismatch
 }
 
 struct FlagResolution: Encodable, Decodable, Equatable {
@@ -68,20 +69,41 @@ extension FlagResolution {
             }
 
             let parsedValue = try getValue(path: parsedKey.path, value: value)
-            let pathValue: T = getTyped(value: parsedValue) ?? defaultValue
+            let typedValue: T? = getTyped(value: parsedValue)
 
             if resolvedFlag.resolveReason == .match {
                 var resolveReason: ResolveReason = .match
                 if self.context != context {
                     resolveReason = .stale
                 }
-                return Evaluation(
-                    value: pathValue,
-                    variant: resolvedFlag.variant,
-                    reason: resolveReason,
-                    errorCode: nil,
-                    errorMessage: nil
-                )
+                if let typedValue = typedValue {
+                    return Evaluation(
+                        value: typedValue,
+                        variant: resolvedFlag.variant,
+                        reason: resolveReason,
+                        errorCode: nil,
+                        errorMessage: nil
+                    )
+                } else {
+                    // `null` type from backend instructs to use client-side default value
+                    if parsedValue == .init(null: ()) {
+                        return Evaluation(
+                            value: defaultValue,
+                            variant: resolvedFlag.variant,
+                            reason: resolveReason,
+                            errorCode: nil,
+                            errorMessage: nil
+                        )
+                    } else {
+                        return Evaluation(
+                            value: defaultValue,
+                            variant: nil,
+                            reason: .error,
+                            errorCode: .typeMismatch,
+                            errorMessage: nil
+                        )
+                    }
+                }
             } else {
                 return Evaluation(
                     value: defaultValue,
diff --git a/Sources/ConfidenceProvider/ConfidenceFeatureProvider.swift b/Sources/ConfidenceProvider/ConfidenceFeatureProvider.swift
index b20960cc..538518a3 100644
--- a/Sources/ConfidenceProvider/ConfidenceFeatureProvider.swift
+++ b/Sources/ConfidenceProvider/ConfidenceFeatureProvider.swift
@@ -145,6 +145,8 @@ extension Evaluation {
                 throw OpenFeatureError.flagNotFoundError(key: self.errorMessage ?? "unknown key")
             case .evaluationError:
                 throw OpenFeatureError.generalError(message: self.errorMessage ?? "unknown error")
+            case .typeMismatch:
+                throw OpenFeatureError.typeMismatchError
             }
         }
         return ProviderEvaluation(
diff --git a/Tests/ConfidenceTests/ConfidenceIntegrationTest.swift b/Tests/ConfidenceTests/ConfidenceIntegrationTest.swift
index c3f2c096..8c949b6c 100644
--- a/Tests/ConfidenceTests/ConfidenceIntegrationTest.swift
+++ b/Tests/ConfidenceTests/ConfidenceIntegrationTest.swift
@@ -30,7 +30,7 @@ class ConfidenceIntegrationTests: XCTestCase {
             .withContext(initialContext: ctx)
             .build()
         try await confidence.fetchAndActivate()
-        let intResult = confidence.getEvaluation(key: "\(resolveFlag).my-integer", defaultValue: "1")
+        let intResult = confidence.getEvaluation(key: "\(resolveFlag).my-integer", defaultValue: 1)
         let boolResult = confidence.getEvaluation(key: "\(resolveFlag).my-boolean", defaultValue: false)
 
 
diff --git a/Tests/ConfidenceTests/ConfidenceTest.swift b/Tests/ConfidenceTests/ConfidenceTest.swift
index b5e83780..4d8c3f96 100644
--- a/Tests/ConfidenceTests/ConfidenceTest.swift
+++ b/Tests/ConfidenceTests/ConfidenceTest.swift
@@ -618,6 +618,44 @@ class ConfidenceTest: XCTestCase {
         }
     }
 
+    func testTypeMismatch() async throws {
+        class FakeClient: ConfidenceResolveClient {
+            var resolveStats: Int = 0
+            var resolvedValues: [ResolvedValue] = []
+            func resolve(ctx: ConfidenceStruct) async throws -> ResolvesResult {
+                self.resolveStats += 1
+                return .init(resolvedValues: resolvedValues, resolveToken: "token")
+            }
+        }
+
+        let client = FakeClient()
+        client.resolvedValues = [
+            ResolvedValue(
+                variant: "control",
+                value: .init(structure: ["size": .init(boolean: true)]),
+                flag: "flag",
+                resolveReason: .match)
+        ]
+
+        let confidence = Confidence.Builder(clientSecret: "test")
+            .withContext(initialContext: ["targeting_key": .init(string: "user1")])
+            .withFlagResolverClient(flagResolver: client)
+            .withFlagApplier(flagApplier: flagApplier)
+            .build()
+
+        try await confidence.fetchAndActivate()
+        let evaluation = confidence.getEvaluation(
+            key: "flag.size",
+            defaultValue: 1)
+
+        XCTAssertEqual(client.resolveStats, 1)
+        XCTAssertEqual(evaluation.value, 1)
+        XCTAssertEqual(evaluation.errorCode, .typeMismatch)
+        XCTAssertNil(evaluation.errorMessage, "")
+        XCTAssertEqual(evaluation.reason, .error)
+        XCTAssertEqual(evaluation.variant, nil)
+    }
+
     func testConcurrentActivate() async {
         for _ in 1...100 {
             Task {