diff --git a/src/ble/att_server.c b/src/ble/att_server.c
index 3cd91b3bc..b436387a5 100644
--- a/src/ble/att_server.c
+++ b/src/ble/att_server.c
@@ -548,9 +548,10 @@ static void att_server_handle_can_send_now(void){
     hci_con_handle_t request_con_handle   = HCI_CON_HANDLE_INVALID;
     hci_con_handle_t last_send_con_handle = HCI_CON_HANDLE_INVALID;
     int can_send_now = 1;
-    int phase;
+    int phase_index;
 
-    for (phase = ATT_SERVER_RUN_PHASE_1_REQUESTS; phase <= ATT_SERVER_RUN_PHASE_3_NOTIFICATIONS; phase++){
+    for (phase_index = ATT_SERVER_RUN_PHASE_1_REQUESTS; phase_index <= ATT_SERVER_RUN_PHASE_3_NOTIFICATIONS; phase_index++){
+        att_server_run_phase_t phase = (att_server_run_phase_t) phase_index;
         hci_con_handle_t skip_connections_until = att_server_last_can_send_now;
         while (1){
             btstack_linked_list_iterator_t it;
diff --git a/src/ble/sm.c b/src/ble/sm.c
index 9f9d7e73e..4a4c59d41 100644
--- a/src/ble/sm.c
+++ b/src/ble/sm.c
@@ -3184,7 +3184,6 @@ static int sm_validate_stk_generation_method(void){
             return (sm_accepted_stk_generation_methods & SM_STK_GENERATION_METHOD_OOB) != 0;
         case NUMERIC_COMPARISON:
             return (sm_accepted_stk_generation_methods & SM_STK_GENERATION_METHOD_NUMERIC_COMPARISON) != 0;
-            return 1;
         default:
             return 0;
     }
diff --git a/src/btstack_crypto.c b/src/btstack_crypto.c
index 58427da07..e1713ad32 100644
--- a/src/btstack_crypto.c
+++ b/src/btstack_crypto.c
@@ -671,11 +671,13 @@ static void btstack_crypto_run(void){
             btstack_crypto_wait_for_hci_result = 1;
             hci_send_cmd(&hci_le_generate_dhkey, &btstack_crypto_ec_p192->public_key[0], &btstack_crypto_ec_p192->public_key[32]);
 #endif
-#endif
-            break;        
-		default:
-			break;
-	}
+            break;
+
+#endif /* ENABLE_ECC_P256 */
+
+        default:
+            break;
+    }
 }
 
 static void btstack_crypto_handle_random_data(const uint8_t * data, uint16_t len){
diff --git a/src/btstack_slip.c b/src/btstack_slip.c
index 06dc6295e..89e4994ca 100644
--- a/src/btstack_slip.c
+++ b/src/btstack_slip.c
@@ -113,9 +113,9 @@ uint8_t btstack_slip_encoder_get_byte(void){
 					encoder_state = SLIP_ENCODER_SEND_DD;
 					return 0xdb;
 				default:
-					return next_byte;
+                    break;
 			}
-			break;
+			return next_byte;
 		case SLIP_ENCODER_SEND_DC:
 			encoder_state = SLIP_ENCODER_DEFAULT;
 			return 0x0dc;