diff --git a/test/api/test-buffer.c b/test/api/test-buffer.c
index 5c98a9a16..5fba3b228 100644
--- a/test/api/test-buffer.c
+++ b/test/api/test-buffer.c
@@ -92,14 +92,14 @@ fixture_init (fixture_t *fixture, gconstpointer user_data)
 }
 
 static void
-fixture_finish (fixture_t *fixture, gconstpointer user_data)
+fixture_finish (fixture_t *fixture, gconstpointer user_data HB_UNUSED)
 {
   hb_buffer_destroy (fixture->buffer);
 }
 
 
 static void
-test_buffer_properties (fixture_t *fixture, gconstpointer user_data)
+test_buffer_properties (fixture_t *fixture, gconstpointer user_data HB_UNUSED)
 {
   hb_buffer_t *b = fixture->buffer;
   hb_unicode_funcs_t *ufuncs;
@@ -294,7 +294,7 @@ test_buffer_contents (fixture_t *fixture, gconstpointer user_data)
 }
 
 static void
-test_buffer_positions (fixture_t *fixture, gconstpointer user_data)
+test_buffer_positions (fixture_t *fixture, gconstpointer user_data HB_UNUSED)
 {
   hb_buffer_t *b = fixture->buffer;
   unsigned int i, len, len2;
@@ -319,7 +319,7 @@ test_buffer_positions (fixture_t *fixture, gconstpointer user_data)
 }
 
 static void
-test_buffer_allocation (fixture_t *fixture, gconstpointer user_data)
+test_buffer_allocation (fixture_t *fixture, gconstpointer user_data HB_UNUSED)
 {
   hb_buffer_t *b = fixture->buffer;
 
diff --git a/test/api/test-multithread.c b/test/api/test-multithread.c
index de288b6a4..e1e7eb531 100644
--- a/test/api/test-multithread.c
+++ b/test/api/test-multithread.c
@@ -49,7 +49,7 @@ static int num_iters = 200;
 static hb_font_t *font;
 static hb_buffer_t *ref_buffer;
 
-pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 
 static void
 fill_the_buffer (hb_buffer_t *buffer)
@@ -105,7 +105,6 @@ static void
 test_body (void)
 {
   int i;
-  int num_threads = 30;
   pthread_t *threads = calloc (num_threads, sizeof (pthread_t));
   hb_buffer_t **buffers = calloc (num_threads, sizeof (hb_buffer_t *));