diff --git a/fastpair/dataparser/fast_pair_data_parser.cc b/fastpair/dataparser/fast_pair_data_parser.cc
index 904dfd20..6275e762 100644
--- a/fastpair/dataparser/fast_pair_data_parser.cc
+++ b/fastpair/dataparser/fast_pair_data_parser.cc
@@ -65,10 +65,9 @@ void ConvertVectorsToArrays(
 void FastPairDataParser::GetHexModelIdFromServiceData(
     const std::vector<uint8_t>& service_data,
     GetHexModelIdFromServiceDataCallback callback) {
-  callback.on_retrieved_cb(
-      FastPairDecoder::HasModelId(&service_data)
-          ? FastPairDecoder::GetHexModelIdFromServiceData(&service_data)
-          : std::nullopt);
+  callback(FastPairDecoder::HasModelId(&service_data)
+               ? FastPairDecoder::GetHexModelIdFromServiceData(&service_data)
+               : std::nullopt);
 }
 
 void FastPairDataParser::ParseDecryptedResponse(
@@ -76,7 +75,7 @@ void FastPairDataParser::ParseDecryptedResponse(
     const std::vector<uint8_t>& encrypted_response_bytes,
     ParseDecryptResponseCallback callback) {
   if (!ValidateInputSizes(aes_key_bytes, encrypted_response_bytes)) {
-    callback.on_decrypted_cb(std::nullopt);
+    callback(std::nullopt);
     return;
   }
 
@@ -84,8 +83,7 @@ void FastPairDataParser::ParseDecryptedResponse(
   std::array<uint8_t, kEncryptedDataByteSize> bytes;
   ConvertVectorsToArrays(aes_key_bytes, encrypted_response_bytes, key, bytes);
 
-  callback.on_decrypted_cb(
-      FastPairDecryption::ParseDecryptResponse(key, bytes));
+  callback(FastPairDecryption::ParseDecryptResponse(key, bytes));
 }
 
 void FastPairDataParser::ParseDecryptedPasskey(
@@ -93,7 +91,7 @@ void FastPairDataParser::ParseDecryptedPasskey(
     const std::vector<uint8_t>& encrypted_passkey_bytes,
     ParseDecryptPasskeyCallback callback) {
   if (!ValidateInputSizes(aes_key_bytes, encrypted_passkey_bytes)) {
-    callback.on_decrypted_cb(std::nullopt);
+    callback(std::nullopt);
     return;
   }
 
@@ -101,7 +99,7 @@ void FastPairDataParser::ParseDecryptedPasskey(
   std::array<uint8_t, kEncryptedDataByteSize> bytes;
   ConvertVectorsToArrays(aes_key_bytes, encrypted_passkey_bytes, key, bytes);
 
-  callback.on_decrypted_cb(FastPairDecryption::ParseDecryptPasskey(key, bytes));
+  callback(FastPairDecryption::ParseDecryptPasskey(key, bytes));
 }
 
 }  // namespace fastpair
diff --git a/fastpair/dataparser/fast_pair_data_parser.h b/fastpair/dataparser/fast_pair_data_parser.h
index b3fb9247..926d9ec6 100644
--- a/fastpair/dataparser/fast_pair_data_parser.h
+++ b/fastpair/dataparser/fast_pair_data_parser.h
@@ -32,23 +32,19 @@
 namespace nearby {
 namespace fastpair {
 
-struct GetHexModelIdFromServiceDataCallback {
-  absl::AnyInvocable<void(std::optional<absl::string_view>)> on_retrieved_cb =
-      [](std::optional<absl::string_view>) {};
-};
 
-struct ParseDecryptResponseCallback {
-  absl::AnyInvocable<void(std::optional<DecryptedResponse>)> on_decrypted_cb =
-      [](std::optional<DecryptedResponse>) {};
-};
-
-struct ParseDecryptPasskeyCallback {
-  absl::AnyInvocable<void(std::optional<DecryptedPasskey>)> on_decrypted_cb =
-      [](std::optional<DecryptedPasskey>) {};
-};
 
 // This class is responsible for parsing the untrusted bytes for Fast Pair.
 class FastPairDataParser {
+  using GetHexModelIdFromServiceDataCallback =
+      absl::AnyInvocable<void(std::optional<absl::string_view>)>;
+
+  using ParseDecryptResponseCallback =
+      absl::AnyInvocable<void(std::optional<DecryptedResponse>)>;
+
+  using ParseDecryptPasskeyCallback =
+      absl::AnyInvocable<void(std::optional<DecryptedPasskey>)>;
+
  public:
   // Gets the hex string representation of the device's model ID from the
   // service data.
diff --git a/fastpair/dataparser/fast_pair_data_parser_test.cc b/fastpair/dataparser/fast_pair_data_parser_test.cc
index 1bab9f4b..9e661814 100644
--- a/fastpair/dataparser/fast_pair_data_parser_test.cc
+++ b/fastpair/dataparser/fast_pair_data_parser_test.cc
@@ -14,21 +14,16 @@
 
 #include "fastpair/dataparser/fast_pair_data_parser.h"
 
-#include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <array>
-#include <functional>
 #include <iterator>
 #include <memory>
 #include <optional>
 #include <string>
-#include <utility>
 #include <vector>
 
-#include "gmock/gmock.h"
-#include "protobuf-matchers/protocol-buffer-matchers.h"
 #include "gtest/gtest.h"
 #include "absl/strings/string_view.h"
 #include "absl/synchronization/notification.h"
@@ -55,16 +50,11 @@ TEST(FastPairDataParserTest, GetHexModelIdFromServiceDataUnsucessfully) {
           .Build()
           ->CreateServiceData();
   absl::Notification notification;
-  GetHexModelIdFromServiceDataCallback callback;
-  callback.on_retrieved_cb =
-      [&notification](std::optional<absl::string_view> model_id) {
+  FastPairDataParser::GetHexModelIdFromServiceData(
+      service_data, [&notification](std::optional<absl::string_view> model_id) {
         EXPECT_EQ(model_id, std::nullopt);
         notification.Notify();
-      };
-
-  FastPairDataParser::GetHexModelIdFromServiceData(service_data,
-                                                   std::move(callback));
-
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -75,15 +65,11 @@ TEST(FastPairDataParserTest, GetHexModelIdFromServiceDataSuccessfully) {
           .Build()
           ->CreateServiceData();
   absl::Notification notification;
-  GetHexModelIdFromServiceDataCallback callback;
-  callback.on_retrieved_cb =
-      [&notification](std::optional<absl::string_view> model_id) {
+  FastPairDataParser::GetHexModelIdFromServiceData(
+      service_data, [&notification](std::optional<absl::string_view> model_id) {
         EXPECT_EQ(model_id, kModelId);
         notification.Notify();
-      };
-
-  FastPairDataParser::GetHexModelIdFromServiceData(service_data,
-                                                   std::move(callback));
+      });
 
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
@@ -119,15 +105,12 @@ TEST(FastPairDataParserTest, DecryptResponseUnsuccessfullyWithInvalidAesKey) {
                                        encrypted_bytes_array.end());
 
   absl::Notification notification;
-  ParseDecryptResponseCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedResponse(
+      kAesKeyBytes, encrypted_bytes,
       [&notification](std::optional<DecryptedResponse> response) {
         EXPECT_FALSE(response.has_value());
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedResponse(kAesKeyBytes, encrypted_bytes,
-                                             std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -162,15 +145,12 @@ TEST(FastPairDataParserTest, DecryptResponseUnsuccessfullyWithInvalidResponse) {
                                        encrypted_bytes_array.end() - 1);
 
   absl::Notification notification;
-  ParseDecryptResponseCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedResponse(
+      kAesKeyBytes, encrypted_bytes,
       [&notification](std::optional<DecryptedResponse> response) {
         EXPECT_FALSE(response.has_value());
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedResponse(kAesKeyBytes, encrypted_bytes,
-                                             std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -204,19 +184,17 @@ TEST(FastPairDataParserTest, DecryptResponseSuccessfully) {
                                        encrypted_bytes_array.end());
 
   absl::Notification notification;
-  ParseDecryptResponseCallback callback;
-  callback.on_decrypted_cb = [&notification, &kAddressBytes, &kSalt](
-                                 std::optional<DecryptedResponse> response) {
-    EXPECT_TRUE(response.has_value());
-    EXPECT_EQ(response.value().message_type,
-              FastPairMessageType::kKeyBasedPairingResponse);
-    EXPECT_EQ(response.value().address_bytes, kAddressBytes);
-    EXPECT_EQ(response.value().salt, kSalt);
-    notification.Notify();
-  };
-
-  FastPairDataParser::ParseDecryptedResponse(kAesKeyBytes, encrypted_bytes,
-                                             std::move(callback));
+  FastPairDataParser::ParseDecryptedResponse(
+      kAesKeyBytes, encrypted_bytes,
+      [&notification, &kAddressBytes,
+       &kSalt](std::optional<DecryptedResponse> response) {
+        EXPECT_TRUE(response.has_value());
+        EXPECT_EQ(response.value().message_type,
+                  FastPairMessageType::kKeyBasedPairingResponse);
+        EXPECT_EQ(response.value().address_bytes, kAddressBytes);
+        EXPECT_EQ(response.value().salt, kSalt);
+        notification.Notify();
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -251,15 +229,12 @@ TEST(FastPairDataParserTest, DecryptPasskeyUnsuccessfullyWithInvalidAesKey) {
                                        encrypted_bytes_array.end());
 
   absl::Notification notification;
-  ParseDecryptPasskeyCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedPasskey(
+      kAesKeyBytes, encrypted_bytes,
       [&notification](std::optional<DecryptedPasskey> decrypted_passkey) {
         EXPECT_FALSE(decrypted_passkey.has_value());
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedPasskey(kAesKeyBytes, encrypted_bytes,
-                                            std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -293,15 +268,12 @@ TEST(FastPairDataParserTest, DecryptPasskeyUnsuccessfullyWithInvalidPasskey) {
                                        encrypted_bytes_array.end() - 1);
 
   absl::Notification notification;
-  ParseDecryptPasskeyCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedPasskey(
+      kAesKeyBytes, encrypted_bytes,
       [&notification](std::optional<DecryptedPasskey> decrypted_passkey) {
         EXPECT_FALSE(decrypted_passkey.has_value());
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedPasskey(kAesKeyBytes, encrypted_bytes,
-                                            std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -334,8 +306,8 @@ TEST(FastPairDataParserTest, DecryptSeekerPasskeySuccessfully) {
                                        encrypted_bytes_array.end());
 
   absl::Notification notification;
-  ParseDecryptPasskeyCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedPasskey(
+      kAesKeyBytes, encrypted_bytes,
       [&notification, &kPasskey,
        &kSalt](std::optional<DecryptedPasskey> decrypted_passkey) {
         EXPECT_TRUE(decrypted_passkey.has_value());
@@ -344,10 +316,7 @@ TEST(FastPairDataParserTest, DecryptSeekerPasskeySuccessfully) {
         EXPECT_EQ(decrypted_passkey.value().passkey, kPasskey);
         EXPECT_EQ(decrypted_passkey.value().salt, kSalt);
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedPasskey(kAesKeyBytes, encrypted_bytes,
-                                            std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
@@ -380,8 +349,8 @@ TEST(FastPairDataParserTest, DecryptProviderPasskeySuccessfully) {
                                        encrypted_bytes_array.end());
 
   absl::Notification notification;
-  ParseDecryptPasskeyCallback callback;
-  callback.on_decrypted_cb =
+  FastPairDataParser::ParseDecryptedPasskey(
+      kAesKeyBytes, encrypted_bytes,
       [&notification, &kPasskey,
        &kSalt](std::optional<DecryptedPasskey> decrypted_passkey) {
         EXPECT_TRUE(decrypted_passkey.has_value());
@@ -390,10 +359,7 @@ TEST(FastPairDataParserTest, DecryptProviderPasskeySuccessfully) {
         EXPECT_EQ(decrypted_passkey.value().passkey, kPasskey);
         EXPECT_EQ(decrypted_passkey.value().salt, kSalt);
         notification.Notify();
-      };
-
-  FastPairDataParser::ParseDecryptedPasskey(kAesKeyBytes, encrypted_bytes,
-                                            std::move(callback));
+      });
   EXPECT_TRUE(notification.WaitForNotificationWithTimeout(kWaitTimeout));
 }
 
diff --git a/fastpair/handshake/fast_pair_data_encryptor_impl.cc b/fastpair/handshake/fast_pair_data_encryptor_impl.cc
index cddf2918..09d107d9 100644
--- a/fastpair/handshake/fast_pair_data_encryptor_impl.cc
+++ b/fastpair/handshake/fast_pair_data_encryptor_impl.cc
@@ -151,10 +151,7 @@ void FastPairDataEncryptorImpl::ParseDecryptResponse(
   FastPairDataParser::ParseDecryptedResponse(
       std::vector<uint8_t>(shared_secret_key_.begin(),
                            shared_secret_key_.end()),
-      encrypted_response_bytes,
-      {
-          .on_decrypted_cb = std::move(callback),
-      });
+      encrypted_response_bytes, std::move(callback));
 }
 
 void FastPairDataEncryptorImpl::ParseDecryptPasskey(
@@ -167,10 +164,7 @@ void FastPairDataEncryptorImpl::ParseDecryptPasskey(
   FastPairDataParser::ParseDecryptedPasskey(
       std::vector<uint8_t>(shared_secret_key_.begin(),
                            shared_secret_key_.end()),
-      encrypted_passkey_bytes,
-      {
-          .on_decrypted_cb = std::move(callback),
-      });
+      encrypted_passkey_bytes, std::move(callback));
 }
 }  // namespace fastpair
 }  // namespace nearby