diff --git a/teensy/Makefile b/teensy/Makefile
index 62ccd875a4..54e6ef050e 100644
--- a/teensy/Makefile
+++ b/teensy/Makefile
@@ -104,7 +104,7 @@ TOOLS_PATH = $(ARDUINO)/hardware/tools
 
 post_compile: $(BUILD)/micropython-mz.hex
 	$(ECHO) "Preparing $@ for upload"
-	$(Q)$(TOOLS_PATH)/teensy_post_compile -file="$(basename $(<F))" -path="$(<D)" -tools="$(TOOLS_PATH)"
+	$(Q)$(TOOLS_PATH)/teensy_post_compile -file="$(basename $(<F))" -path="$(abspath $(<D))" -tools="$(TOOLS_PATH)"
 
 reboot:
 	$(ECHO) "REBOOT"
diff --git a/teensy/usb.c b/teensy/usb.c
index 37c479ec7c..9fb50967db 100644
--- a/teensy/usb.c
+++ b/teensy/usb.c
@@ -1,18 +1,25 @@
 #include <string.h>
+#include <stdint.h>
 
 #include "Arduino.h"
 
+#include "mpconfig.h"
+#include "misc.h"
+#include "qstr.h"
+#include "obj.h"
+#include "runtime.h"
+
 #include "usb.h"
 #include "usb_serial.h"
 
-int usb_vcp_is_connected(void)
+bool usb_vcp_is_connected(void)
 {
   return usb_configuration && (usb_cdc_line_rtsdtr & (USB_SERIAL_DTR | USB_SERIAL_RTS));
 }
 
-int usb_vcp_is_enabled(void)
+bool usb_vcp_is_enabled(void)
 {
-  return 1;
+  return true;
 }
 
 void usb_vcp_set_interrupt_char(int c) {
@@ -25,9 +32,14 @@ int usb_vcp_rx_num(void) {
   return usb_serial_available();
 }
 
-int usb_vcp_recv_byte(void)
+int usb_vcp_recv_byte(uint8_t *ptr)
 {
-  return usb_serial_getchar();
+  int ch = usb_serial_getchar();
+  if (ch < 0) {
+    return 0;
+  }
+  *ptr = ch;
+  return 1;
 }
 
 void usb_vcp_send_str(const char* str)
diff --git a/teensy/usb.h b/teensy/usb.h
deleted file mode 100644
index 8f32309ecb..0000000000
--- a/teensy/usb.h
+++ /dev/null
@@ -1,9 +0,0 @@
-void usb_init(void);
-int usb_vcp_is_enabled(void);
-int usb_vcp_is_connected(void);
-int usb_vcp_rx_any(void);
-char usb_vcp_rx_get(void);
-void usb_vcp_send_str(const char* str);
-void usb_vcp_send_strn(const char* str, int len);
-void usb_vcp_send_strn_cooked(const char *str, int len);
-void usb_hid_send_report(uint8_t *buf); // 4 bytes for mouse: ?, x, y, ?