diff --git a/cdc_XR21B1411.h b/cdc_XR21B1411.h
index 347f0df6..eb830c95 100644
--- a/cdc_XR21B1411.h
+++ b/cdc_XR21B1411.h
@@ -60,7 +60,7 @@ e-mail   :  support@circuitsathome.com
 #define XR_REG_ERROR_STATUS_OVERRUN             (0x0010U) // RX OVERRUN ERROR
 #define XR_REG_ERROR_STATUS_PARITY              (0x0020U) // PARITY ERROR
 #define XR_REG_ERROR_STATUS_FRAME               (0x0040U) // FRAMING ERROR
-#define XR_REG_ERROR_STATUS_BREAK               (0x0080U) // BREAK IS BEING DETECTED
+#define XR_REG_ERROR_STATUS_BREAKING            (0x0080U) // BREAK IS BEING DETECTED
 
 #define XR_REG_TX_BREAK                         (0x0C0AU) // TRANSMIT BREAK. 0X0001-0XFFE TIME IN MS, 0X0000 STOP, 0X0FFF BREAK ON
 
diff --git a/cdcacm.h b/cdcacm.h
index dd248100..e403928e 100644
--- a/cdcacm.h
+++ b/cdcacm.h
@@ -203,7 +203,7 @@ public:
         uint8_t Poll();
 
         bool available(void) {
-
+                return false;
         };
 
         virtual uint8_t GetAddress() {
diff --git a/cdcftdi.h b/cdcftdi.h
index a9b0e950..46854f82 100644
--- a/cdcftdi.h
+++ b/cdcftdi.h
@@ -80,9 +80,11 @@ class FTDIAsyncOper {
 public:
 
         virtual uint8_t OnInit(FTDI *pftdi) {
+                return 0;
         };
 
         virtual uint8_t OnRelease(FTDI *pftdi) {
+                return 0;
         };
 };
 
diff --git a/hid.h b/hid.h
index 14507183..3b45f4ec 100644
--- a/hid.h
+++ b/hid.h
@@ -156,7 +156,7 @@ protected:
         void PrintEndpointDescriptor(const USB_ENDPOINT_DESCRIPTOR* ep_ptr);
         void PrintHidDescriptor(const USB_HID_DESCRIPTOR *pDesc);
 
-        virtual HIDReportParser* GetReportParser(uint8_t id) {};
+        virtual HIDReportParser* GetReportParser(uint8_t id) { return NULL;};
 
 public:
 
@@ -167,7 +167,7 @@ public:
                 return pUsb;
         };
 
-        virtual bool SetReportParser(uint8_t id, HIDReportParser *prs) {};
+        virtual bool SetReportParser(uint8_t id, HIDReportParser *prs) { return false; };
 
         uint8_t SetProtocol(uint8_t iface, uint8_t protocol);
         uint8_t GetProtocol(uint8_t iface, uint8_t* dataptr);
diff --git a/settings.h b/settings.h
index 30281617..74d8d1e8 100644
--- a/settings.h
+++ b/settings.h
@@ -123,7 +123,7 @@ e-mail   :  support@circuitsathome.com
 #define EXT_RAM 0
 #endif
 
-#if defined(CORE_TEENSY) && (defined(__MK20DX128__) || defined(__MK20DX256__))
+#if defined(CORE_TEENSY) && (defined(__MK20DX128__) || defined(__MK20DX256__) || defined(__MK66FX1M0__))
 #define USING_SPI4TEENSY3 USE_SPI4TEENSY3
 #else
 #define USING_SPI4TEENSY3 0