self._i2c = _I2C(frequency=frequency)
             return
         if detector.board.microchip_mcp2221:
-            if "BLINKA_FORCEBOARD" not in os.environ:
-                from adafruit_blinka.microcontroller.mcp2221.i2c import I2C as _I2C
-            elif os.environ["BLINKA_FORCEBOARD"] == "MICROCHIP_MCP2221":
-                from adafruit_blinka.microcontroller.fake_mcp2221.i2c import I2C as _I2C
+            from adafruit_blinka.microcontroller.mcp2221.i2c import I2C as _I2C
+
+            self._i2c = _I2C(frequency=frequency)
+            return
+
+        if detector.board.OS_AGNOSTIC_BOARD:
+            from adafruit_blinka.microcontroller.generic_agnostic_board.i2c import (
+                I2C as _I2C,
+            )
+
             self._i2c = _I2C(frequency=frequency)
             return
+
         if detector.board.greatfet_one:
             from adafruit_blinka.microcontroller.nxp_lpc4330.i2c import I2C as _I2C
 
             from adafruit_blinka.microcontroller.generic_linux.spi import SPI as _SPI
         elif detector.board.ftdi_ft2232h:
             from adafruit_blinka.microcontroller.ftdi_mpsse.mpsse.spi import SPI as _SPI
+        elif detector.board.OS_AGNOSTIC_BOARD:
+            from adafruit_blinka.microcontroller.generic_agnostic_board.spi import (
+                SPI as _SPI,
+            )
         else:
             from adafruit_blinka.microcontroller.generic_micropython.spi import (
                 SPI as _SPI,