diff --git a/config.py.EXAMPLE b/config.py.EXAMPLE
index 19e9b0f..f002627 100644
--- a/config.py.EXAMPLE
+++ b/config.py.EXAMPLE
@@ -41,7 +41,7 @@ gpio_door = 18
 #   max6675 - bitbang SPI interface
 max31855 = 1
 max6675 = 0
-max31855spi = 0
+max31855spi = 0 # if you use this one, you MUST reassign the default GPIO pins
 
 ### Thermocouple Connection (using bitbang interfaces)
 gpio_sensor_cs = 27
diff --git a/lib/oven.py b/lib/oven.py
index 23e4582..fadd42d 100644
--- a/lib/oven.py
+++ b/lib/oven.py
@@ -20,6 +20,15 @@ try:
         import Adafruit_GPIO.SPI as SPI
         from max31855spi import MAX31855SPI, MAX31855SPIError
         log.info("import MAX31855SPI")
+        spi_reserved_gpio = [7, 8, 9, 10, 11]
+        if config.gpio_air in spi_reserved_gpio:
+            raise Exception("gpio_air pin %s collides with SPI pins %s" % (config.gpio_air, spi_reserved_gpio))
+        if config.gpio_cool in spi_reserved_gpio:
+            raise Exception("gpio_cool pin %s collides with SPI pins %s" % (config.gpio_cool, spi_reserved_gpio))
+        if config.gpio_door in spi_reserved_gpio:
+            raise Exception("gpio_door pin %s collides with SPI pins %s" % (config.gpio_door, spi_reserved_gpio))
+        if config.gpio_heat in spi_reserved_gpio:
+            raise Exception("gpio_heat pin %s collides with SPI pins %s" % (config.gpio_heat, spi_reserved_gpio))
     if config.max6675:
         from max6675 import MAX6675, MAX6675Error
         log.info("import MAX6675")