diff --git a/src/a2dp.c b/src/a2dp.c
index f3dbb7be5..34c5bf103 100644
--- a/src/a2dp.c
+++ b/src/a2dp.c
@@ -43,7 +43,6 @@
 #endif
 #include "a2dp-sbc.h"
 #include "ba-config.h"
-#include "ba-transport.h"
 #include "shared/a2dp-codecs.h"
 #include "shared/log.h"
 
@@ -390,13 +389,3 @@ const char *a2dp_check_strerror(
 	debug("Unknown error code: %#x", err);
 	return "Check error";
 }
-
-int a2dp_transport_init(
-		struct ba_transport *t) {
-	return t->a2dp.sep->transport_init(t);
-}
-
-int a2dp_transport_start(
-		struct ba_transport *t) {
-	return t->a2dp.sep->transport_start(t);
-}
diff --git a/src/a2dp.h b/src/a2dp.h
index d451310f8..0018133ed 100644
--- a/src/a2dp.h
+++ b/src/a2dp.h
@@ -240,9 +240,4 @@ enum a2dp_check_err a2dp_check_configuration(
 const char *a2dp_check_strerror(
 		enum a2dp_check_err err);
 
-int a2dp_transport_init(
-		struct ba_transport *t);
-int a2dp_transport_start(
-		struct ba_transport *t);
-
 #endif
diff --git a/src/ba-transport.c b/src/ba-transport.c
index 1c5a628eb..f0ace4b63 100644
--- a/src/ba-transport.c
+++ b/src/ba-transport.c
@@ -421,6 +421,9 @@ struct ba_transport *ba_transport_new_a2dp(
 	t->a2dp.sep = sep;
 	memcpy(&t->a2dp.configuration, configuration, sep->config.caps_size);
 
+	t->acquire = transport_acquire_bt_a2dp;
+	t->release = transport_release_bt_a2dp;
+
 	err |= transport_pcm_init(&t->a2dp.pcm,
 			is_sink ? BA_TRANSPORT_PCM_MODE_SOURCE : BA_TRANSPORT_PCM_MODE_SINK,
 			t, true);
@@ -432,17 +435,18 @@ struct ba_transport *ba_transport_new_a2dp(
 	if (err != 0)
 		goto fail;
 
+	/* do codec-specific initialization */
+	if (sep->transport_init(t) != 0) {
+		errno = EINVAL;
+		goto fail;
+	}
+
 	if ((errno = pthread_create(&t->thread_manager_thread_id,
 			NULL, PTHREAD_FUNC(transport_thread_manager), t)) != 0) {
 		t->thread_manager_thread_id = config.main_thread;
 		goto fail;
 	}
 
-	t->acquire = transport_acquire_bt_a2dp;
-	t->release = transport_release_bt_a2dp;
-
-	a2dp_transport_init(t);
-
 	storage_pcm_data_sync(&t->a2dp.pcm);
 	storage_pcm_data_sync(&t->a2dp.pcm_bc);
 
@@ -552,26 +556,6 @@ struct ba_transport *ba_transport_new_sco(
 	 * there is no other option than the CVSD codec. */
 	t->codec_id = HFP_CODEC_CVSD;
 
-	err |= transport_pcm_init(&t->sco.pcm_spk,
-			is_ag ? BA_TRANSPORT_PCM_MODE_SINK : BA_TRANSPORT_PCM_MODE_SOURCE,
-			t, true);
-
-	err |= transport_pcm_init(&t->sco.pcm_mic,
-			is_ag ? BA_TRANSPORT_PCM_MODE_SOURCE : BA_TRANSPORT_PCM_MODE_SINK,
-			t, false);
-
-	if (err != 0)
-		goto fail;
-
-	if ((errno = pthread_create(&t->thread_manager_thread_id,
-			NULL, PTHREAD_FUNC(transport_thread_manager), t)) != 0) {
-		t->thread_manager_thread_id = config.main_thread;
-		goto fail;
-	}
-
-	t->acquire = transport_acquire_bt_sco;
-	t->release = transport_release_bt_sco;
-
 #if ENABLE_HFP_CODEC_SELECTION
 	/* Only HFP supports codec selection. */
 	if (profile & BA_TRANSPORT_PROFILE_MASK_HFP &&
@@ -589,7 +573,30 @@ struct ba_transport *ba_transport_new_sco(
 	}
 #endif
 
-	sco_transport_init(t);
+	t->acquire = transport_acquire_bt_sco;
+	t->release = transport_release_bt_sco;
+
+	err |= transport_pcm_init(&t->sco.pcm_spk,
+			is_ag ? BA_TRANSPORT_PCM_MODE_SINK : BA_TRANSPORT_PCM_MODE_SOURCE,
+			t, true);
+
+	err |= transport_pcm_init(&t->sco.pcm_mic,
+			is_ag ? BA_TRANSPORT_PCM_MODE_SOURCE : BA_TRANSPORT_PCM_MODE_SINK,
+			t, false);
+
+	if (err != 0)
+		goto fail;
+
+	if (sco_transport_init(t) != 0) {
+		errno = EINVAL;
+		goto fail;
+	}
+
+	if ((errno = pthread_create(&t->thread_manager_thread_id,
+			NULL, PTHREAD_FUNC(transport_thread_manager), t)) != 0) {
+		t->thread_manager_thread_id = config.main_thread;
+		goto fail;
+	}
 
 	storage_pcm_data_sync(&t->sco.pcm_spk);
 	storage_pcm_data_sync(&t->sco.pcm_mic);
@@ -1026,7 +1033,7 @@ void ba_transport_set_codec(
 		return;
 
 	if (t->profile & BA_TRANSPORT_PROFILE_MASK_A2DP)
-		a2dp_transport_init(t);
+		t->a2dp.sep->transport_init(t);
 	else if (t->profile & BA_TRANSPORT_PROFILE_MASK_SCO)
 		sco_transport_init(t);
 
@@ -1077,7 +1084,7 @@ int ba_transport_start(struct ba_transport *t) {
 	debug("Starting transport: %s", ba_transport_debug_name(t));
 
 	if (t->profile & BA_TRANSPORT_PROFILE_MASK_A2DP)
-		return a2dp_transport_start(t);
+		return t->a2dp.sep->transport_start(t);
 
 	if (t->profile & BA_TRANSPORT_PROFILE_MASK_SCO)
 		return sco_transport_start(t);
diff --git a/src/sco.c b/src/sco.c
index a0421aa45..e839cbfb7 100644
--- a/src/sco.c
+++ b/src/sco.c
@@ -256,7 +256,7 @@ void *sco_dec_thread(struct ba_transport_pcm *pcm) {
 	}
 }
 
-void sco_transport_init(struct ba_transport *t) {
+int sco_transport_init(struct ba_transport *t) {
 
 	t->sco.pcm_spk.format = BA_TRANSPORT_PCM_FORMAT_S16_2LE;
 	t->sco.pcm_spk.channels = 1;
@@ -305,6 +305,7 @@ void sco_transport_init(struct ba_transport *t) {
 				BA_DBUS_PCM_UPDATE_CODEC |
 				BA_DBUS_PCM_UPDATE_CLIENT_DELAY);
 
+	return 0;
 }
 
 int sco_transport_start(struct ba_transport *t) {
diff --git a/src/sco.h b/src/sco.h
index a32db9391..c9cc23c8a 100644
--- a/src/sco.h
+++ b/src/sco.h
@@ -1,6 +1,6 @@
 /*
  * BlueALSA - sco.h
- * Copyright (c) 2016-2023 Arkadiusz Bokowy
+ * Copyright (c) 2016-2024 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -20,7 +20,7 @@
 #include "ba-transport.h"
 
 int sco_setup_connection_dispatcher(struct ba_adapter *a);
-void sco_transport_init(struct ba_transport *t);
+int sco_transport_init(struct ba_transport *t);
 int sco_transport_start(struct ba_transport *t);
 
 #endif
diff --git a/test/test-ba.c b/test/test-ba.c
index f629a9c60..c456564e2 100644
--- a/test/test-ba.c
+++ b/test/test-ba.c
@@ -49,8 +49,6 @@
 /* Keep persistent storage in the current directory. */
 #define TEST_BLUEALSA_STORAGE_DIR "storage-test-ba"
 
-int a2dp_transport_init(struct ba_transport *t) { (void)t; return 0; }
-int a2dp_transport_start(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_alsa_seq_create(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_alsa_seq_delete(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_start(struct ba_transport *t) { (void)t; return 0; }
@@ -313,6 +311,11 @@ CK_START_TEST(test_ba_transport_pcm_format) {
 
 } CK_END_TEST
 
+static int sep_transport_init(struct ba_transport *t) {
+	(void)t;
+	return 0;
+}
+
 CK_START_TEST(test_ba_transport_pcm_volume) {
 
 	struct ba_adapter *a;
@@ -325,7 +328,9 @@ CK_START_TEST(test_ba_transport_pcm_volume) {
 	ck_assert_ptr_ne(d = ba_device_new(a, &addr), NULL);
 	ck_assert_int_eq(storage_device_clear(d), 0);
 
-	struct a2dp_sep sep = { .config = { .type = A2DP_SINK, .codec_id = A2DP_CODEC_SBC } };
+	struct a2dp_sep sep = {
+		.config = { .type = A2DP_SINK, .codec_id = A2DP_CODEC_SBC },
+		.transport_init = sep_transport_init };
 	a2dp_sbc_t configuration = { .channel_mode = SBC_CHANNEL_MODE_STEREO };
 	ck_assert_ptr_ne(t_a2dp = ba_transport_new_a2dp(d,
 				BA_TRANSPORT_PROFILE_A2DP_SINK, "/owner", "/path/a2dp", &sep,
@@ -410,7 +415,9 @@ CK_START_TEST(test_storage) {
 	ck_assert_ptr_ne(a = ba_adapter_new(0), NULL);
 	ck_assert_ptr_ne(d = ba_device_new(a, &addr), NULL);
 
-	struct a2dp_sep sep = { .config = { .type = A2DP_SINK, .codec_id = A2DP_CODEC_SBC } };
+	struct a2dp_sep sep = {
+		.config = { .type = A2DP_SINK, .codec_id = A2DP_CODEC_SBC },
+		.transport_init = sep_transport_init };
 	a2dp_sbc_t configuration = { .channel_mode = SBC_CHANNEL_MODE_STEREO };
 	ck_assert_ptr_ne(t = ba_transport_new_a2dp(d,
 				BA_TRANSPORT_PROFILE_A2DP_SINK, "/owner", "/path", &sep,
diff --git a/test/test-io.c b/test/test-io.c
index 158b6738b..2eea60f9b 100644
--- a/test/test-io.c
+++ b/test/test-io.c
@@ -726,8 +726,9 @@ static struct ba_transport *test_transport_new_a2dp(
 	if (input_bt_file != NULL)
 		configuration = &btdin->a2dp_configuration;
 #endif
-	struct ba_transport *t = ba_transport_new_a2dp(device, profile, ":test",
-			dbus_path, sep, configuration);
+	struct ba_transport *t;
+	ck_assert_ptr_nonnull(t = ba_transport_new_a2dp(device, profile, ":test",
+				dbus_path, sep, configuration));
 	t->acquire = test_transport_acquire;
 	t->release = test_transport_release_bt_a2dp;
 	return t;
@@ -772,7 +773,9 @@ CK_START_TEST(test_a2dp_sbc) {
 
 CK_START_TEST(test_a2dp_sbc_invalid_config) {
 
-	const a2dp_sbc_t config_sbc_invalid = { 0 };
+	const a2dp_sbc_t config_sbc_invalid = {
+		.sampling_freq = SBC_SAMPLING_FREQ_44100,
+		.channel_mode = SBC_CHANNEL_MODE_STEREO };
 	struct ba_transport *t = test_transport_new_a2dp(device1,
 			BA_TRANSPORT_PROFILE_A2DP_SOURCE, "/path/sbc", &a2dp_sbc_source,
 			&config_sbc_invalid);
diff --git a/test/test-rfcomm.c b/test/test-rfcomm.c
index 4374dd9fb..8b050d738 100644
--- a/test/test-rfcomm.c
+++ b/test/test-rfcomm.c
@@ -58,8 +58,6 @@ static void dbus_update_counters_wait(unsigned int *counter, unsigned int value)
 	pthread_mutex_unlock(&dbus_update_mtx);
 }
 
-int a2dp_transport_init(struct ba_transport *t) { (void)t; return 0; }
-int a2dp_transport_start(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_alsa_seq_create(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_alsa_seq_delete(struct ba_transport *t) { (void)t; return 0; }
 int midi_transport_start(struct ba_transport *t) { (void)t; return 0; }