diff --git a/tools/testing/selftests/alsa/mixer-test.c b/tools/testing/selftests/alsa/mixer-test.c
index 79ffbca429ee..ac40c7d17152 100644
--- a/tools/testing/selftests/alsa/mixer-test.c
+++ b/tools/testing/selftests/alsa/mixer-test.c
@@ -71,7 +71,8 @@ struct ctl_data *ctl_list = NULL;
 #endif
 
 #ifndef LIB_HAS_LOAD_STRING
-int snd_config_load_string(snd_config_t **config, const char *s, size_t size)
+static int snd_config_load_string(snd_config_t **config, const char *s,
+				  size_t size)
 {
 	snd_input_t *input;
 	snd_config_t *dst;
@@ -99,7 +100,7 @@ int snd_config_load_string(snd_config_t **config, const char *s, size_t size)
 }
 #endif
 
-void find_controls(void)
+static void find_controls(void)
 {
 	char name[32];
 	int card, ctl, err;
@@ -222,7 +223,7 @@ void find_controls(void)
  * Block for up to timeout ms for an event, returns a negative value
  * on error, 0 for no event and 1 for an event.
  */
-int wait_for_event(struct ctl_data *ctl, int timeout)
+static int wait_for_event(struct ctl_data *ctl, int timeout)
 {
 	unsigned short revents;
 	snd_ctl_event_t *event;
@@ -285,8 +286,9 @@ int wait_for_event(struct ctl_data *ctl, int timeout)
 	return 1;
 }
 
-bool ctl_value_index_valid(struct ctl_data *ctl, snd_ctl_elem_value_t *val,
-			   int index)
+static bool ctl_value_index_valid(struct ctl_data *ctl,
+				  snd_ctl_elem_value_t *val,
+				  int index)
 {
 	long int_val;
 	long long int64_val;
@@ -397,7 +399,7 @@ bool ctl_value_index_valid(struct ctl_data *ctl, snd_ctl_elem_value_t *val,
  * Check that the provided value meets the constraints for the
  * provided control.
  */
-bool ctl_value_valid(struct ctl_data *ctl, snd_ctl_elem_value_t *val)
+static bool ctl_value_valid(struct ctl_data *ctl, snd_ctl_elem_value_t *val)
 {
 	int i;
 	bool valid = true;
@@ -413,7 +415,7 @@ bool ctl_value_valid(struct ctl_data *ctl, snd_ctl_elem_value_t *val)
  * Check that we can read the default value and it is valid. Write
  * tests use the read value to restore the default.
  */
-void test_ctl_get_value(struct ctl_data *ctl)
+static void test_ctl_get_value(struct ctl_data *ctl)
 {
 	int err;
 
@@ -448,9 +450,9 @@ void test_ctl_get_value(struct ctl_data *ctl)
 			 ctl->card->card, ctl->elem);
 }
 
-bool show_mismatch(struct ctl_data *ctl, int index,
-		   snd_ctl_elem_value_t *read_val,
-		   snd_ctl_elem_value_t *expected_val)
+static bool show_mismatch(struct ctl_data *ctl, int index,
+			  snd_ctl_elem_value_t *read_val,
+			  snd_ctl_elem_value_t *expected_val)
 {
 	long long expected_int, read_int;
 
@@ -513,9 +515,9 @@ bool show_mismatch(struct ctl_data *ctl, int index,
  * the write to fail, for verifying that invalid writes don't corrupt
  * anything.
  */
-int write_and_verify(struct ctl_data *ctl,
-		     snd_ctl_elem_value_t *write_val,
-		     snd_ctl_elem_value_t *expected_val)
+static int write_and_verify(struct ctl_data *ctl,
+			    snd_ctl_elem_value_t *write_val,
+			    snd_ctl_elem_value_t *expected_val)
 {
 	int err, i;
 	bool error_expected, mismatch_shown;
@@ -622,7 +624,7 @@ int write_and_verify(struct ctl_data *ctl,
  * Make sure we can write the default value back to the control, this
  * should validate that at least some write works.
  */
-void test_ctl_write_default(struct ctl_data *ctl)
+static void test_ctl_write_default(struct ctl_data *ctl)
 {
 	int err;
 
@@ -655,7 +657,7 @@ void test_ctl_write_default(struct ctl_data *ctl)
 			 ctl->card->card, ctl->elem);
 }
 
-bool test_ctl_write_valid_boolean(struct ctl_data *ctl)
+static bool test_ctl_write_valid_boolean(struct ctl_data *ctl)
 {
 	int err, i, j;
 	bool fail = false;
@@ -676,7 +678,7 @@ bool test_ctl_write_valid_boolean(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_valid_integer(struct ctl_data *ctl)
+static bool test_ctl_write_valid_integer(struct ctl_data *ctl)
 {
 	int err;
 	int i;
@@ -706,7 +708,7 @@ bool test_ctl_write_valid_integer(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_valid_integer64(struct ctl_data *ctl)
+static bool test_ctl_write_valid_integer64(struct ctl_data *ctl)
 {
 	int err, i;
 	long long j, step;
@@ -734,7 +736,7 @@ bool test_ctl_write_valid_integer64(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_valid_enumerated(struct ctl_data *ctl)
+static bool test_ctl_write_valid_enumerated(struct ctl_data *ctl)
 {
 	int err, i, j;
 	bool fail = false;
@@ -755,7 +757,7 @@ bool test_ctl_write_valid_enumerated(struct ctl_data *ctl)
 	return !fail;
 }
 
-void test_ctl_write_valid(struct ctl_data *ctl)
+static void test_ctl_write_valid(struct ctl_data *ctl)
 {
 	bool pass;
 	int err;
@@ -808,8 +810,8 @@ void test_ctl_write_valid(struct ctl_data *ctl)
 			 ctl->card->card, ctl->elem);
 }
 
-bool test_ctl_write_invalid_value(struct ctl_data *ctl,
-				  snd_ctl_elem_value_t *val)
+static bool test_ctl_write_invalid_value(struct ctl_data *ctl,
+					 snd_ctl_elem_value_t *val)
 {
 	int err;
 	long val_read;
@@ -830,7 +832,7 @@ bool test_ctl_write_invalid_value(struct ctl_data *ctl,
 	return !ctl_value_valid(ctl, val);
 }
 
-bool test_ctl_write_invalid_boolean(struct ctl_data *ctl)
+static bool test_ctl_write_invalid_boolean(struct ctl_data *ctl)
 {
 	int err, i;
 	long val_read;
@@ -849,7 +851,7 @@ bool test_ctl_write_invalid_boolean(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_invalid_integer(struct ctl_data *ctl)
+static bool test_ctl_write_invalid_integer(struct ctl_data *ctl)
 {
 	int i;
 	bool fail = false;
@@ -895,7 +897,7 @@ bool test_ctl_write_invalid_integer(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_invalid_integer64(struct ctl_data *ctl)
+static bool test_ctl_write_invalid_integer64(struct ctl_data *ctl)
 {
 	int i;
 	bool fail = false;
@@ -941,7 +943,7 @@ bool test_ctl_write_invalid_integer64(struct ctl_data *ctl)
 	return !fail;
 }
 
-bool test_ctl_write_invalid_enumerated(struct ctl_data *ctl)
+static bool test_ctl_write_invalid_enumerated(struct ctl_data *ctl)
 {
 	int err, i;
 	unsigned int val_read;
@@ -973,7 +975,7 @@ bool test_ctl_write_invalid_enumerated(struct ctl_data *ctl)
 }
 
 
-void test_ctl_write_invalid(struct ctl_data *ctl)
+static void test_ctl_write_invalid(struct ctl_data *ctl)
 {
 	bool pass;
 	int err;
@@ -1026,13 +1028,13 @@ void test_ctl_write_invalid(struct ctl_data *ctl)
 			 ctl->card->card, ctl->elem);
 }
 
-void test_ctl_event_missing(struct ctl_data *ctl)
+static void test_ctl_event_missing(struct ctl_data *ctl)
 {
 	ksft_test_result(!ctl->event_missing, "event_missing.%d.%d\n",
 			 ctl->card->card, ctl->elem);
 }
 
-void test_ctl_event_spurious(struct ctl_data *ctl)
+static void test_ctl_event_spurious(struct ctl_data *ctl)
 {
 	ksft_test_result(!ctl->event_spurious, "event_spurious.%d.%d\n",
 			 ctl->card->card, ctl->elem);
