diff --git a/platformio/builder/scripts/frameworks/arduino.py b/platformio/builder/scripts/frameworks/arduino.py
index 16164d8d..558852a8 100644
--- a/platformio/builder/scripts/frameworks/arduino.py
+++ b/platformio/builder/scripts/frameworks/arduino.py
@@ -198,6 +198,20 @@ if env.get("PLATFORM") == "teensy":
         "ARDUINO=10600",
         "TEENSYDUINO=%d" % ARDUINO_VERSION
     ]
+
+    USB_FLAGS = (
+        "USB_HID",
+        "USB_SERIAL_HID",
+        "USB_DISK",
+        "USB_DISK_SDFLASH",
+        "USB_MIDI",
+        "USB_RAWHID",
+        "USB_FLIGHTSIM",
+        "USB_DISABLED"
+    )
+
+    if not any(f in env.get("BUILD_FLAGS", []) for f in USB_FLAGS):
+        env.Append(CPPDEFINES=["USB_SERIAL"])
 else:
     ARDUINO_USBDEFINES += ["ARDUINO=%d" % ARDUINO_VERSION]
 
@@ -310,6 +324,8 @@ if BOARD_BUILDOPTS.get("core", None) == "teensy":
         with open(file_path, "w") as fp:
             fp.write(content)
 
+    env.Append(CPPPATH=[join("$PLATFORMFW_DIR", "cores")])
+
 #
 # Target: Build Core Library
 #
diff --git a/platformio/builder/scripts/teensy.py b/platformio/builder/scripts/teensy.py
index 43e293f3..c01c67e8 100644
--- a/platformio/builder/scripts/teensy.py
+++ b/platformio/builder/scripts/teensy.py
@@ -40,7 +40,6 @@ elif env.get("BOARD_OPTIONS", {}).get("build", {}).get("core") == "teensy3":
 
 env.Append(
     CPPDEFINES=[
-        "USB_SERIAL",
         "LAYOUT_US_ENGLISH"
     ],