diff --git a/test/gatt_client/mock.c b/test/gatt_client/mock.c
index 08121e1bf..561a6cd59 100644
--- a/test/gatt_client/mock.c
+++ b/test/gatt_client/mock.c
@@ -17,7 +17,8 @@ static void (*registered_hci_event_handler) (uint8_t packet_type, uint16_t chann
 static btstack_linked_list_t     connections;
 static const uint16_t max_mtu = 23;
 static uint8_t  l2cap_stack_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + 8 + max_mtu];	// pre buffer + HCI Header + L2CAP header
-uint16_t gatt_client_handle = 0x40;
+static uint16_t gatt_client_handle = 0x40;
+static hci_connection_t hci_connection;
 
 uint16_t get_gatt_client_handle(void){
 	return gatt_client_handle;
@@ -149,8 +150,7 @@ hci_connection_t * hci_connection_for_bd_addr_and_type(bd_addr_t addr, bd_addr_t
 	return NULL;
 }
 hci_connection_t * hci_connection_for_handle(hci_con_handle_t con_handle){
-	printf("hci_connection_for_handle not implemented in mock backend\n");
-	return NULL;
+	return &hci_connection;
 }
 void hci_connections_get_iterator(btstack_linked_list_iterator_t *it){
 	// printf("hci_connections_get_iterator not implemented in mock backend\n");
diff --git a/test/tlv_posix/Makefile b/test/tlv_posix/Makefile
index 885b21c83..e3354b968 100644
--- a/test/tlv_posix/Makefile
+++ b/test/tlv_posix/Makefile
@@ -19,7 +19,6 @@ CFLAGS  = \
     -DBTSTACK_TEST \
     -g \
     -Wall \
-    -Wmissing-prototypes \
     -Wnarrowing \
     -I. \
     -I.. \
diff --git a/test/tlv_posix/tlv_test.c b/test/tlv_posix/tlv_test.c
index 3d9163a29..cadaf83ca 100644
--- a/test/tlv_posix/tlv_test.c
+++ b/test/tlv_posix/tlv_test.c
@@ -12,6 +12,8 @@
 
 #define TEST_DB "/tmp/test.tlv"
 
+#define TAG(a,b,c,d) ( ((a)<<24) | ((b)<<16) | ((c)<<8) | (d) )
+
 /// TLV
 TEST_GROUP(BSTACK_TLV){
 	const btstack_tlv_t * btstack_tlv_impl;
@@ -38,13 +40,13 @@ TEST_GROUP(BSTACK_TLV){
 };
 
 TEST(BSTACK_TLV, TestMissingTag){
-	uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
 	int size = btstack_tlv_impl->get_tag(&btstack_tlv_context, tag, NULL, 0);
 	CHECK_EQUAL(size, 0);
 }
 
 TEST(BSTACK_TLV, TestWriteRead){
-	uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
 	uint8_t  data = 7;
 	uint8_t  buffer = data;
 	btstack_tlv_impl->store_tag(&btstack_tlv_context, tag, &buffer, 1);
@@ -55,7 +57,7 @@ TEST(BSTACK_TLV, TestWriteRead){
 }
 
 TEST(BSTACK_TLV, TestWriteWriteRead){
-	uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
 	uint8_t  data = 7;
 	uint8_t  buffer = data;
 	btstack_tlv_impl->store_tag(&btstack_tlv_context, tag, &buffer, 1);
@@ -69,8 +71,8 @@ TEST(BSTACK_TLV, TestWriteWriteRead){
 }
 
 TEST(BSTACK_TLV, TestWriteABARead){
-	uint32_t tag_a = 'aaaa';
-	uint32_t tag_b = 'bbbb';
+	uint32_t tag_a = TAG('a','a','a','a');
+	uint32_t tag_b = TAG('b','b','b','b');;
 	uint8_t  data = 7;
 	uint8_t  buffer = data;
 	btstack_tlv_impl->store_tag(&btstack_tlv_context, tag_a, &buffer, 1);
@@ -87,7 +89,7 @@ TEST(BSTACK_TLV, TestWriteABARead){
 }
 
 TEST(BSTACK_TLV, TestWriteDeleteRead){
-	uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
 	uint8_t  data = 7;
 	uint8_t  buffer = data;
 	btstack_tlv_impl->store_tag(&btstack_tlv_context, tag, &buffer, 1);
@@ -100,7 +102,7 @@ TEST(BSTACK_TLV, TestWriteDeleteRead){
 }
 
 TEST(BSTACK_TLV, TestMigrate){
-	uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
 	uint8_t  data[8];
 	memcpy(data, "01234567", 8);
 
@@ -145,7 +147,7 @@ TEST(BSTACK_TLV, TestMigrate2){
 }
 
 TEST(BSTACK_TLV, TestWriteResetRead){
-    uint32_t tag = 'abcd';
+	uint32_t tag = TAG('a','b','c','d');
     uint8_t  data = 7;
     uint8_t  buffer = data;
     btstack_tlv_impl->store_tag(&btstack_tlv_context, tag, &buffer, 1);