diff --git a/spa/examples/adapter-control.c b/spa/examples/adapter-control.c
index 3434d2752..956b4d427 100644
--- a/spa/examples/adapter-control.c
+++ b/spa/examples/adapter-control.c
@@ -906,9 +906,9 @@ static void run_async_sink(struct data *data)
 		printf("got error %d\n", res);
 }
 
-static char *getscale(uint32_t scale)
+static const char *getscale(uint32_t scale)
 {
-	char *scale_s = NULL;
+	const char *scale_s = NULL;
 
 	if (scale == SPA_AUDIO_VOLUME_RAMP_LINEAR)
 		scale_s = LINEAR;
diff --git a/spa/plugins/alsa/alsa-compress-offload-sink.c b/spa/plugins/alsa/alsa-compress-offload-sink.c
index b30350c8a..df8e43a25 100644
--- a/spa/plugins/alsa/alsa-compress-offload-sink.c
+++ b/spa/plugins/alsa/alsa-compress-offload-sink.c
@@ -843,7 +843,7 @@ static int parse_device(struct impl *this)
 
 	nextptr = device + 3;
 	for (value_index = 0; ; ++value_index) {
-		char *value_label;
+		const char *value_label;
 
 		switch (value_index) {
 		case 0: value_label = "card"; break;
diff --git a/spa/plugins/bluez5/backend-native.c b/spa/plugins/bluez5/backend-native.c
index 2e81adf3a..57281137c 100644
--- a/spa/plugins/bluez5/backend-native.c
+++ b/spa/plugins/bluez5/backend-native.c
@@ -2399,7 +2399,7 @@ static int register_profile(struct impl *backend, const char *profile, const cha
 	DBusMessageIter it[4];
 	dbus_bool_t autoconnect;
 	dbus_uint16_t version, chan, features;
-	char *str;
+	const char *str;
 
 	if (!(backend->enabled_profiles & spa_bt_profile_from_uuid(uuid)))
 		return -ECANCELED;
diff --git a/spa/plugins/bluez5/bluez5-dbus.c b/spa/plugins/bluez5/bluez5-dbus.c
index ac07d10f2..62cb37ddd 100644
--- a/spa/plugins/bluez5/bluez5-dbus.c
+++ b/spa/plugins/bluez5/bluez5-dbus.c
@@ -1435,7 +1435,7 @@ static bool device_remove_device_set(struct spa_bt_device *device, const char *p
 int spa_bt_format_vendor_product_id(uint16_t source_id, uint16_t vendor_id, uint16_t product_id,
 		char *vendor_str, int vendor_str_size, char *product_str, int product_str_size)
 {
-	char *source_str;
+	const char *source_str;
 
 	switch (source_id) {
 	case SOURCE_ID_USB:
diff --git a/src/modules/module-rtp-session.c b/src/modules/module-rtp-session.c
index 0df26a89b..9733f16f0 100644
--- a/src/modules/module-rtp-session.c
+++ b/src/modules/module-rtp-session.c
@@ -1335,7 +1335,8 @@ static struct service *make_service(struct impl *impl, const struct service_info
 	if (spa_streq(service_name, "_pipewire-audio._udp")) {
 		uint32_t mask = 0;
 		for (l = txt; l && compatible; l = l->next) {
-			char *key, *value, *k = NULL;
+			const char *k = NULL;
+			char *key, *value;
 
 			if (avahi_string_list_get_pair(l, &key, &value, NULL) != 0)
 				break;
diff --git a/src/tools/pw-link.c b/src/tools/pw-link.c
index 23c559db1..78b0d5680 100644
--- a/src/tools/pw-link.c
+++ b/src/tools/pw-link.c
@@ -197,7 +197,9 @@ static char *port_alias(char *buffer, int size, struct object *n, struct object
 static void print_port(struct data *data, const char *prefix, struct object *n,
 		struct object *p, bool verbose)
 {
-	char buffer[1024], id[64] = "", *prefix2 = "";
+	char buffer[1024], id[64] = "";
+	const char *prefix2 = "";
+
 	if (data->opt_id) {
 		snprintf(id, sizeof(id), "%4d ", p->id);
 		prefix2 = "     ";
diff --git a/test/pwtest.c b/test/pwtest.c
index 8a9d1cf67..80217d999 100644
--- a/test/pwtest.c
+++ b/test/pwtest.c
@@ -1207,7 +1207,7 @@ static char* make_xdg_runtime_dir(void)
 	time_t t = time(NULL);
 	struct tm *tm = localtime(&t);
 	char *dir;
-	char *tmpdir = getenv("TMPDIR");
+	const char *tmpdir = getenv("TMPDIR");
 	char path[PATH_MAX];
 	FILE *fp;
 
diff --git a/test/test-logger.c b/test/test-logger.c
index 3ad29da0b..0b3648b05 100644
--- a/test/test-logger.c
+++ b/test/test-logger.c
@@ -232,7 +232,7 @@ PWTEST(logger_debug_env_alpha)
 	enum spa_log_level level = pwtest_get_iteration(current_test);
 	enum spa_log_level default_level = pw_log_level;
 	struct spa_log *default_logger = pw_log_get();
-	char *lvl = NULL;
+	const char *lvl = NULL;
 	char *oldenv = getenv("PIPEWIRE_DEBUG");
 
 	if (oldenv)
@@ -276,7 +276,7 @@ PWTEST(logger_debug_env_topic_all)
 	struct spa_log *default_logger = pw_log_get();
 	char *oldenv = getenv("PIPEWIRE_DEBUG");
 	char lvlstr[32];
-	char *lvl = "X";
+	const char *lvl = "X";
 
 	if (oldenv)
 		oldenv = strdup(oldenv);
diff --git a/test/test-spa-json.c b/test/test-spa-json.c
index 629e29c82..063a14ed9 100644
--- a/test/test-spa-json.c
+++ b/test/test-spa-json.c
@@ -166,7 +166,7 @@ PWTEST(json_encode)
 	return PWTEST_PASS;
 }
 
-static void test_array(char *str, char **vals)
+static void test_array(const char *str, const char * const vals[])
 {
 	struct spa_json it[2];
 	char val[256];
@@ -183,12 +183,12 @@ static void test_array(char *str, char **vals)
 
 PWTEST(json_array)
 {
-	test_array("FL,FR", (char *[]){ "FL", "FR", NULL });
-	test_array(" FL , FR ", (char *[]){ "FL", "FR", NULL });
-	test_array("[ FL , FR ]", (char *[]){ "FL", "FR", NULL });
-	test_array("[FL FR]", (char *[]){ "FL", "FR", NULL });
-	test_array("FL FR", (char *[]){ "FL", "FR", NULL });
-	test_array("[ FL FR ]", (char *[]){ "FL", "FR", NULL });
+	test_array("FL,FR", (const char *[]){ "FL", "FR", NULL });
+	test_array(" FL , FR ", (const char *[]){ "FL", "FR", NULL });
+	test_array("[ FL , FR ]", (const char *[]){ "FL", "FR", NULL });
+	test_array("[FL FR]", (const char *[]){ "FL", "FR", NULL });
+	test_array("FL FR", (const char *[]){ "FL", "FR", NULL });
+	test_array("[ FL FR ]", (const char *[]){ "FL", "FR", NULL });
 
 	return PWTEST_PASS;
 }