diff --git a/bricks/ev3dev/pb_ev3dev_types.h b/bricks/ev3dev/pb_ev3dev_types.h
index e32a50d85..d8664ff83 100644
--- a/bricks/ev3dev/pb_ev3dev_types.h
+++ b/bricks/ev3dev/pb_ev3dev_types.h
@@ -22,10 +22,10 @@ GrxFont *pb_ev3dev_Font_obj_get_font(mp_const_obj_t obj);
 
 // class Image
 
-const mp_obj_type_t pb_type_ev3dev_Image;
+extern const mp_obj_type_t pb_type_ev3dev_Image;
 
 // class Speaker
 
-const mp_obj_type_t pb_type_ev3dev_Speaker;
+extern const mp_obj_type_t pb_type_ev3dev_Speaker;
 
 #endif // PYBRICKS_INCLUDED_BRICKS_EV3DEV_TYPES_H
diff --git a/lib/pbio/include/pbio/control.h b/lib/pbio/include/pbio/control.h
index 2e8127146..09723deba 100644
--- a/lib/pbio/include/pbio/control.h
+++ b/lib/pbio/include/pbio/control.h
@@ -61,11 +61,11 @@ typedef bool (*pbio_control_on_target_t)(pbio_trajectory_t *trajectory,
     bool stalled);
 
 // Functions to check whether motion is done
-pbio_control_on_target_t pbio_control_on_target_always;
-pbio_control_on_target_t pbio_control_on_target_never;
-pbio_control_on_target_t pbio_control_on_target_angle;
-pbio_control_on_target_t pbio_control_on_target_time;
-pbio_control_on_target_t pbio_control_on_target_stalled;
+extern pbio_control_on_target_t pbio_control_on_target_always;
+extern pbio_control_on_target_t pbio_control_on_target_never;
+extern pbio_control_on_target_t pbio_control_on_target_angle;
+extern pbio_control_on_target_t pbio_control_on_target_time;
+extern pbio_control_on_target_t pbio_control_on_target_stalled;
 
 typedef enum {
     PBIO_CONTROL_NONE,   /**< No control */
diff --git a/pybricks/common.h b/pybricks/common.h
index e4301a217..805ad645e 100644
--- a/pybricks/common.h
+++ b/pybricks/common.h
@@ -28,8 +28,8 @@ mp_obj_t common_LightArray_obj_make_new(pb_device_t *pbdev, uint8_t light_mode,
 #ifdef PYBRICKS_PY_COMMON_LIGHT_MATRIX
 #include <pbio/light_matrix.h>
 // pybricks._common.LightMatrix()
-const uint8_t pb_digits_5x2[10][5];
-const uint8_t pb_font_5x5[95][5];
+extern const uint8_t pb_digits_5x2[10][5];
+extern const uint8_t pb_font_5x5[95][5];
 mp_obj_t pb_type_Lightmatrix_obj_new(pbio_light_matrix_t *light_matrix);
 #endif
 
@@ -39,7 +39,7 @@ mp_obj_t pb_type_Keypad_obj_new(uint8_t number_of_buttons, const pb_obj_enum_mem
 #endif
 
 // pybricks._common.Battery()
-const mp_obj_module_t pb_module_battery;
+extern const mp_obj_module_t pb_module_battery;
 
 
 #if PYBRICKS_PY_COMMON_MOTORS
@@ -48,7 +48,7 @@ const mp_obj_module_t pb_module_battery;
 #include <pbio/servo.h>
 
 // pybricks._common.Control()
-const mp_obj_type_t pb_type_Control;
+extern const mp_obj_type_t pb_type_Control;
 mp_obj_t common_Control_obj_make_new(pbio_control_t *control);
 
 // pybricks._common.Logger()
@@ -62,7 +62,7 @@ typedef struct _common_Motor_obj_t {
     mp_obj_t logger;
 } common_Motor_obj_t;
 
-const mp_obj_type_t pb_type_Motor;
+extern const mp_obj_type_t pb_type_Motor;
 
 // pybricks._common.DCMotor()
 typedef struct _common_DCMotor_obj_t {
@@ -70,7 +70,7 @@ typedef struct _common_DCMotor_obj_t {
     pbio_dcmotor_t *dcmotor;
 } common_DCMotor_obj_t;
 
-const mp_obj_type_t pb_type_DCMotor;
+extern const mp_obj_type_t pb_type_DCMotor;
 
 // Nonstatic objects shared between Motor and DCMotor
 void common_DCMotor_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind);
@@ -82,7 +82,7 @@ MP_DECLARE_CONST_FUN_OBJ_1(common_DCMotor_brake_obj);
 
 #if PYBRICKS_PY_COMMON_SPEAKER
 
-const mp_obj_type_t pb_type_Speaker;
+extern const mp_obj_type_t pb_type_Speaker;
 
 #endif // PYBRICKS_PY_COMMON_SPEAKER
 
diff --git a/pybricks/ev3devices.h b/pybricks/ev3devices.h
index 6c5e176f9..03bcdedc8 100644
--- a/pybricks/ev3devices.h
+++ b/pybricks/ev3devices.h
@@ -10,13 +10,13 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_ev3devices;
+extern const mp_obj_module_t pb_module_ev3devices;
 
-const mp_obj_type_t pb_type_ev3devices_ColorSensor;
-const mp_obj_type_t pb_type_ev3devices_InfraredSensor;
-const mp_obj_type_t pb_type_ev3devices_GyroSensor;
-const mp_obj_type_t pb_type_ev3devices_TouchSensor;
-const mp_obj_type_t pb_type_ev3devices_UltrasonicSensor;
+extern const mp_obj_type_t pb_type_ev3devices_ColorSensor;
+extern const mp_obj_type_t pb_type_ev3devices_InfraredSensor;
+extern const mp_obj_type_t pb_type_ev3devices_GyroSensor;
+extern const mp_obj_type_t pb_type_ev3devices_TouchSensor;
+extern const mp_obj_type_t pb_type_ev3devices_UltrasonicSensor;
 
 #endif // PYBRICKS_PY_EV3DEVICES
 
diff --git a/pybricks/experimental.h b/pybricks/experimental.h
index 5e360d190..bf99d4023 100644
--- a/pybricks/experimental.h
+++ b/pybricks/experimental.h
@@ -10,7 +10,7 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_experimental;
+extern const mp_obj_module_t pb_module_experimental;
 
 #endif // PYBRICKS_PY_EXPERIMENTAL
 
diff --git a/pybricks/geometry.h b/pybricks/geometry.h
index 62e14155b..bab57fdf6 100644
--- a/pybricks/geometry.h
+++ b/pybricks/geometry.h
@@ -12,9 +12,9 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_geometry;
+extern const mp_obj_module_t pb_module_geometry;
 
-const mp_obj_type_t pb_type_Matrix;
+extern const mp_obj_type_t pb_type_Matrix;
 
 typedef struct _pb_type_Matrix_obj_t {
     mp_obj_base_t base;
diff --git a/pybricks/hubs.h b/pybricks/hubs.h
index 266eb8e94..d5bb3e7a0 100644
--- a/pybricks/hubs.h
+++ b/pybricks/hubs.h
@@ -11,26 +11,26 @@
 #include "py/obj.h"
 
 #if PYBRICKS_HUB_MOVEHUB
-const mp_obj_type_t pb_type_MoveHub;
+extern const mp_obj_type_t pb_type_MoveHub;
 #endif
 #if PYBRICKS_HUB_CITYHUB
-const mp_obj_type_t pb_type_CityHub;
+extern const mp_obj_type_t pb_type_CityHub;
 #endif
 #if PYBRICKS_HUB_TECHNICHUB
-const mp_obj_type_t pb_type_TechnicHub;
+extern const mp_obj_type_t pb_type_TechnicHub;
 #endif
 #ifdef PYBRICKS_HUB_PRIMEHUB
-const mp_obj_type_t pb_type_PrimeHub;
-const mp_obj_type_t pb_type_InventorHub;
+extern const mp_obj_type_t pb_type_PrimeHub;
+extern const mp_obj_type_t pb_type_InventorHub;
 #endif
 #if PYBRICKS_HUB_NXTBRICK
-const mp_obj_type_t pb_type_NXTBrick;
+extern const mp_obj_type_t pb_type_NXTBrick;
 #endif
 #if PYBRICKS_HUB_EV3BRICK
-const mp_obj_type_t pb_type_EV3Brick;
+extern const mp_obj_type_t pb_type_EV3Brick;
 #endif
 
-const mp_obj_module_t pb_module_hubs;
+extern const mp_obj_module_t pb_module_hubs;
 
 #endif // PYBRICKS_PY_HUBS
 
diff --git a/pybricks/iodevices.h b/pybricks/iodevices.h
index b8bffa31e..a2d3b504b 100644
--- a/pybricks/iodevices.h
+++ b/pybricks/iodevices.h
@@ -10,21 +10,21 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_iodevices;
+extern const mp_obj_module_t pb_module_iodevices;
 
 #if PYBRICKS_PY_PUPDEVICES
 
-const mp_obj_type_t pb_type_iodevices_PUPDevice;
+extern const mp_obj_type_t pb_type_iodevices_PUPDevice;
 
 #endif // PYBRICKS_PY_PUPDEVICES
 
 #if PYBRICKS_PY_EV3DEVICES
 
-const mp_obj_type_t pb_type_iodevices_LUMPDevice;
-const mp_obj_type_t pb_type_iodevices_AnalogSensor;
-const mp_obj_type_t pb_type_iodevices_Ev3devSensor;
-const mp_obj_type_t pb_type_iodevices_I2CDevice;
-const mp_obj_type_t pb_type_iodevices_UARTDevice;
+extern const mp_obj_type_t pb_type_iodevices_LUMPDevice;
+extern const mp_obj_type_t pb_type_iodevices_AnalogSensor;
+extern const mp_obj_type_t pb_type_iodevices_Ev3devSensor;
+extern const mp_obj_type_t pb_type_iodevices_I2CDevice;
+extern const mp_obj_type_t pb_type_iodevices_UARTDevice;
 
 #endif // PYBRICKS_PY_EV3DEVICES
 
diff --git a/pybricks/media.h b/pybricks/media.h
index 952aac4cd..4d73268d8 100644
--- a/pybricks/media.h
+++ b/pybricks/media.h
@@ -10,7 +10,7 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_media;
+extern const mp_obj_module_t pb_module_media;
 
 #endif // PYBRICKS_PY_MEDIA
 
diff --git a/pybricks/nxtdevices.h b/pybricks/nxtdevices.h
index 9cae3811c..2d6f6cb66 100644
--- a/pybricks/nxtdevices.h
+++ b/pybricks/nxtdevices.h
@@ -10,15 +10,15 @@
 
 #include "py/obj.h"
 
-const mp_obj_module_t pb_module_nxtdevices;
-
-const mp_obj_type_t pb_type_nxtdevices_ColorSensor;
-const mp_obj_type_t pb_type_nxtdevices_EnergyMeter;
-const mp_obj_type_t pb_type_nxtdevices_LightSensor;
-const mp_obj_type_t pb_type_nxtdevices_SoundSensor;
-const mp_obj_type_t pb_type_nxtdevices_TemperatureSensor;
-const mp_obj_type_t pb_type_nxtdevices_TouchSensor;
-const mp_obj_type_t pb_type_nxtdevices_UltrasonicSensor;
+extern const mp_obj_module_t pb_module_nxtdevices;
+
+extern const mp_obj_type_t pb_type_nxtdevices_ColorSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_EnergyMeter;
+extern const mp_obj_type_t pb_type_nxtdevices_LightSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_SoundSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_TemperatureSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_TouchSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_UltrasonicSensor;
 
 int32_t analog_scale(int32_t mvolts, int32_t mvolts_min, int32_t mvolts_max, bool invert);
 
diff --git a/pybricks/parameters.h b/pybricks/parameters.h
index 6f3470605..0b4ad22ca 100644
--- a/pybricks/parameters.h
+++ b/pybricks/parameters.h
@@ -16,27 +16,27 @@
 
 #if PYBRICKS_PY_PARAMETERS_BUTTON
 
-const mp_obj_type_t pb_enum_type_Button;
-
-const pb_obj_enum_member_t pb_Button_UP_obj;
-const pb_obj_enum_member_t pb_Button_DOWN_obj;
-const pb_obj_enum_member_t pb_Button_LEFT_obj;
-const pb_obj_enum_member_t pb_Button_RIGHT_obj;
-const pb_obj_enum_member_t pb_Button_RIGHT_PLUS_obj;
-const pb_obj_enum_member_t pb_Button_RIGHT_MINUS_obj;
-const pb_obj_enum_member_t pb_Button_CENTER_obj;
-const pb_obj_enum_member_t pb_Button_LEFT_UP_obj;
-const pb_obj_enum_member_t pb_Button_LEFT_DOWN_obj;
-const pb_obj_enum_member_t pb_Button_LEFT_PLUS_obj;
-const pb_obj_enum_member_t pb_Button_LEFT_MINUS_obj;
-const pb_obj_enum_member_t pb_Button_RIGHT_UP_obj;
-const pb_obj_enum_member_t pb_Button_RIGHT_DOWN_obj;
-const pb_obj_enum_member_t pb_Button_BEACON_obj;
-const pb_obj_enum_member_t pb_Button_BLUETOOTH_obj;
+extern const mp_obj_type_t pb_enum_type_Button;
+
+extern const pb_obj_enum_member_t pb_Button_UP_obj;
+extern const pb_obj_enum_member_t pb_Button_DOWN_obj;
+extern const pb_obj_enum_member_t pb_Button_LEFT_obj;
+extern const pb_obj_enum_member_t pb_Button_RIGHT_obj;
+extern const pb_obj_enum_member_t pb_Button_RIGHT_PLUS_obj;
+extern const pb_obj_enum_member_t pb_Button_RIGHT_MINUS_obj;
+extern const pb_obj_enum_member_t pb_Button_CENTER_obj;
+extern const pb_obj_enum_member_t pb_Button_LEFT_UP_obj;
+extern const pb_obj_enum_member_t pb_Button_LEFT_DOWN_obj;
+extern const pb_obj_enum_member_t pb_Button_LEFT_PLUS_obj;
+extern const pb_obj_enum_member_t pb_Button_LEFT_MINUS_obj;
+extern const pb_obj_enum_member_t pb_Button_RIGHT_UP_obj;
+extern const pb_obj_enum_member_t pb_Button_RIGHT_DOWN_obj;
+extern const pb_obj_enum_member_t pb_Button_BEACON_obj;
+extern const pb_obj_enum_member_t pb_Button_BLUETOOTH_obj;
 
 #endif // PYBRICKS_PY_PARAMETERS_BUTTON
 
-const mp_obj_type_t pb_type_Color;
+extern const mp_obj_type_t pb_type_Color;
 
 typedef struct _pb_type_Color_obj_t {
     mp_obj_base_t base;
@@ -47,45 +47,47 @@ typedef struct _pb_type_Color_obj_t {
 pb_type_Color_obj_t *pb_type_Color_new_empty(void);
 const pbio_color_hsv_t *pb_type_Color_get_hsv(mp_obj_t obj);
 
-const pb_type_Color_obj_t pb_Color_RED_obj;
-const pb_type_Color_obj_t pb_Color_BROWN_obj;
-const pb_type_Color_obj_t pb_Color_ORANGE_obj;
-const pb_type_Color_obj_t pb_Color_YELLOW_obj;
-const pb_type_Color_obj_t pb_Color_GREEN_obj;
-const pb_type_Color_obj_t pb_Color_CYAN_obj;
-const pb_type_Color_obj_t pb_Color_BLUE_obj;
-const pb_type_Color_obj_t pb_Color_VIOLET_obj;
-const pb_type_Color_obj_t pb_Color_MAGENTA_obj;
-const pb_type_Color_obj_t pb_Color_NONE_obj;
-const pb_type_Color_obj_t pb_Color_BLACK_obj;
-const pb_type_Color_obj_t pb_Color_GRAY_obj;
-const pb_type_Color_obj_t pb_Color_WHITE_obj;
+extern const pb_type_Color_obj_t pb_Color_RED_obj;
+extern const pb_type_Color_obj_t pb_Color_BROWN_obj;
+extern const pb_type_Color_obj_t pb_Color_ORANGE_obj;
+extern const pb_type_Color_obj_t pb_Color_YELLOW_obj;
+extern const pb_type_Color_obj_t pb_Color_GREEN_obj;
+extern const pb_type_Color_obj_t pb_Color_CYAN_obj;
+extern const pb_type_Color_obj_t pb_Color_BLUE_obj;
+extern const pb_type_Color_obj_t pb_Color_VIOLET_obj;
+extern const pb_type_Color_obj_t pb_Color_MAGENTA_obj;
+extern const pb_type_Color_obj_t pb_Color_NONE_obj;
+extern const pb_type_Color_obj_t pb_Color_BLACK_obj;
+extern const pb_type_Color_obj_t pb_Color_GRAY_obj;
+extern const pb_type_Color_obj_t pb_Color_WHITE_obj;
 
-const mp_obj_type_t pb_enum_type_Direction;
+extern const mp_obj_type_t pb_enum_type_Direction;
 
-const pb_obj_enum_member_t pb_Direction_CLOCKWISE_obj;
-const pb_obj_enum_member_t pb_Direction_COUNTERCLOCKWISE_obj;
+extern const pb_obj_enum_member_t pb_Direction_CLOCKWISE_obj;
+extern const pb_obj_enum_member_t pb_Direction_COUNTERCLOCKWISE_obj;
 
-const mp_obj_base_t pb_Icon_obj;
+#if PYBRICKS_PY_PARAMETERS_ICON
+extern const mp_obj_base_t pb_Icon_obj;
+#endif
 
-const mp_obj_type_t pb_enum_type_Port;
+extern const mp_obj_type_t pb_enum_type_Port;
 
-const mp_obj_type_t pb_enum_type_Stop;
+extern const mp_obj_type_t pb_enum_type_Stop;
 
-const pb_obj_enum_member_t pb_Stop_COAST_obj;
-const pb_obj_enum_member_t pb_Stop_BRAKE_obj;
-const pb_obj_enum_member_t pb_Stop_HOLD_obj;
+extern const pb_obj_enum_member_t pb_Stop_COAST_obj;
+extern const pb_obj_enum_member_t pb_Stop_BRAKE_obj;
+extern const pb_obj_enum_member_t pb_Stop_HOLD_obj;
 
-const mp_obj_type_t pb_enum_type_Side;
+extern const mp_obj_type_t pb_enum_type_Side;
 
-const pb_obj_enum_member_t pb_Side_BACK_obj;
-const pb_obj_enum_member_t pb_Side_BOTTOM_obj;
-const pb_obj_enum_member_t pb_Side_FRONT_obj;
-const pb_obj_enum_member_t pb_Side_LEFT_obj;
-const pb_obj_enum_member_t pb_Side_RIGHT_obj;
-const pb_obj_enum_member_t pb_Side_TOP_obj;
+extern const pb_obj_enum_member_t pb_Side_BACK_obj;
+extern const pb_obj_enum_member_t pb_Side_BOTTOM_obj;
+extern const pb_obj_enum_member_t pb_Side_FRONT_obj;
+extern const pb_obj_enum_member_t pb_Side_LEFT_obj;
+extern const pb_obj_enum_member_t pb_Side_RIGHT_obj;
+extern const pb_obj_enum_member_t pb_Side_TOP_obj;
 
-const mp_obj_module_t pb_module_parameters;
+extern const mp_obj_module_t pb_module_parameters;
 
 #endif // PYBRICKS_PY_PARAMETERS
 
diff --git a/pybricks/parameters/pb_module_parameters.c b/pybricks/parameters/pb_module_parameters.c
index f3da8b888..ae88b1cd2 100644
--- a/pybricks/parameters/pb_module_parameters.c
+++ b/pybricks/parameters/pb_module_parameters.c
@@ -14,7 +14,9 @@ STATIC const mp_rom_map_elem_t parameters_globals_table[] = {
     #endif
     { MP_ROM_QSTR(MP_QSTR_Color),       MP_ROM_PTR(&pb_type_Color)          },
     { MP_ROM_QSTR(MP_QSTR_Direction),   MP_ROM_PTR(&pb_enum_type_Direction) },
+    #if PYBRICKS_PY_PARAMETERS_ICON
     { MP_ROM_QSTR(MP_QSTR_Icon),        MP_ROM_PTR(&pb_Icon_obj)            },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_Port),        MP_ROM_PTR(&pb_enum_type_Port)      },
     { MP_ROM_QSTR(MP_QSTR_Side),        MP_ROM_PTR(&pb_enum_type_Side)      },
     { MP_ROM_QSTR(MP_QSTR_Stop),        MP_ROM_PTR(&pb_enum_type_Stop)      },
diff --git a/pybricks/pupdevices.h b/pybricks/pupdevices.h
index ab0cf1836..bd064f4fd 100644
--- a/pybricks/pupdevices.h
+++ b/pybricks/pupdevices.h
@@ -12,16 +12,16 @@
 
 #include <pybricks/util_pb/pb_device.h>
 
-const mp_obj_module_t pb_module_pupdevices;
-
-const mp_obj_type_t pb_type_pupdevices_ColorDistanceSensor;
-const mp_obj_type_t pb_type_pupdevices_ColorSensor;
-const mp_obj_type_t pb_type_pupdevices_ForceSensor;
-const mp_obj_type_t pb_type_pupdevices_InfraredSensor;
-const mp_obj_type_t pb_type_pupdevices_Light;
-const mp_obj_type_t pb_type_pupdevices_PFMotor;
-const mp_obj_type_t pb_type_pupdevices_TiltSensor;
-const mp_obj_type_t pb_type_pupdevices_UltrasonicSensor;
+extern const mp_obj_module_t pb_module_pupdevices;
+
+extern const mp_obj_type_t pb_type_pupdevices_ColorDistanceSensor;
+extern const mp_obj_type_t pb_type_pupdevices_ColorSensor;
+extern const mp_obj_type_t pb_type_pupdevices_ForceSensor;
+extern const mp_obj_type_t pb_type_pupdevices_InfraredSensor;
+extern const mp_obj_type_t pb_type_pupdevices_Light;
+extern const mp_obj_type_t pb_type_pupdevices_PFMotor;
+extern const mp_obj_type_t pb_type_pupdevices_TiltSensor;
+extern const mp_obj_type_t pb_type_pupdevices_UltrasonicSensor;
 
 pb_device_t *pupdevices_ColorDistanceSensor__get_device(mp_obj_t obj);
 
diff --git a/pybricks/robotics.h b/pybricks/robotics.h
index 57605a6cc..aaf4b9873 100644
--- a/pybricks/robotics.h
+++ b/pybricks/robotics.h
@@ -13,9 +13,9 @@
 #include "py/obj.h"
 
 
-const mp_obj_type_t pb_type_drivebase;
+extern const mp_obj_type_t pb_type_drivebase;
 
-const mp_obj_module_t pb_module_robotics;
+extern const mp_obj_module_t pb_module_robotics;
 
 #endif // PYBRICKS_PY_ROBOTICS
 
diff --git a/pybricks/tools.h b/pybricks/tools.h
index 487af2ec6..6d980c944 100644
--- a/pybricks/tools.h
+++ b/pybricks/tools.h
@@ -10,9 +10,9 @@
 
 #include "py/obj.h"
 
-const mp_obj_type_t pb_type_StopWatch;
+extern const mp_obj_type_t pb_type_StopWatch;
 
-const mp_obj_module_t pb_module_tools;
+extern const mp_obj_module_t pb_module_tools;
 
 #endif // PYBRICKS_PY_TOOLS