diff --git a/Sources/Packages/Sources/SecureEnclaveSecretKit/SecureEnclaveStore.swift b/Sources/Packages/Sources/SecureEnclaveSecretKit/SecureEnclaveStore.swift
index 61fc722..c9ce8d4 100644
--- a/Sources/Packages/Sources/SecureEnclaveSecretKit/SecureEnclaveStore.swift
+++ b/Sources/Packages/Sources/SecureEnclaveSecretKit/SecureEnclaveStore.swift
@@ -18,6 +18,7 @@ extension SecureEnclave {
         public let id = UUID()
         public let name = String(localized: .secureEnclave)
         private let persistentAuthenticationHandler = PersistentAuthenticationHandler<Secret>()
+        private let signingSerializer = SigningSerializer()
 
         /// Initializes a Store.
         @MainActor public init() {
@@ -38,6 +39,16 @@ extension SecureEnclave {
         // MARK: SecretStore
         
         public func sign(data: Data, with secret: Secret, for provenance: SigningRequestProvenance) async throws -> Data {
+            if secret.attributes.authentication.required {
+                return try await signingSerializer.serialize { [self] in
+                    try await self.performSign(data: data, with: secret, for: provenance)
+                }
+            } else {
+                return try await performSign(data: data, with: secret, for: provenance)
+            }
+        }
+
+        private func performSign(data: Data, with secret: Secret, for provenance: SigningRequestProvenance) async throws -> Data {
             var context: LAContext
             if let existing = await persistentAuthenticationHandler.existingPersistedAuthenticationContext(secret: secret) {
                 context = unsafe existing.context
@@ -85,7 +96,6 @@ extension SecureEnclave {
             default:
                 throw UnsupportedAlgorithmError()
             }
-
         }
 
         public func existingPersistedAuthenticationContext(secret: Secret) async -> PersistedAuthenticationContext? {
diff --git a/Sources/Packages/Sources/SecureEnclaveSecretKit/SigningSerializer.swift b/Sources/Packages/Sources/SecureEnclaveSecretKit/SigningSerializer.swift
new file mode 100644
index 0000000..d813340
--- /dev/null
+++ b/Sources/Packages/Sources/SecureEnclaveSecretKit/SigningSerializer.swift
@@ -0,0 +1,31 @@
+import Foundation
+
+/// Serializes signing operations for protected keys to prevent LAContext conflicts.
+/// macOS only allows one biometric authentication prompt at a time, so concurrent
+/// requests for protected Secure Enclave keys must be queued.
+actor SigningSerializer {
+    private var isProcessing = false
+    private var waiters: [CheckedContinuation<Void, Never>] = []
+
+    func serialize<T: Sendable>(operation: @escaping @Sendable () async throws -> T) async throws -> T {
+        // If someone is already processing, wait in line
+        if isProcessing {
+            await withCheckedContinuation { continuation in
+                waiters.append(continuation)
+            }
+        }
+
+        isProcessing = true
+
+        defer {
+            if let next = waiters.first {
+                waiters.removeFirst()
+                next.resume()
+            } else {
+                isProcessing = false
+            }
+        }
+
+        return try await operation()
+    }
+}