diff --git a/examples/z1/test-adxl345.c b/examples/z1/test-adxl345.c
index 32c29c786..005c8a7b4 100644
--- a/examples/z1/test-adxl345.c
+++ b/examples/z1/test-adxl345.c
@@ -179,8 +179,8 @@ PROCESS_THREAD(accel_process, ev, data) {
     accm_init();
 
     /* Register the callback functions for each interrupt */
-    ACCM_REGISTER_INT1_CB((void *)accm_ff_cb);
-    ACCM_REGISTER_INT2_CB((void *)accm_tap_cb);
+    ACCM_REGISTER_INT1_CB(accm_ff_cb);
+    ACCM_REGISTER_INT2_CB(accm_tap_cb);
 
     /* Set what strikes the corresponding interrupts. Several interrupts per pin is 
       possible. For the eight possible interrupts, see adxl345.h and adxl345 datasheet. */
diff --git a/platform/z1/dev/adxl345.c b/platform/z1/dev/adxl345.c
index 6ddbcbc10..3cd86f6e3 100644
--- a/platform/z1/dev/adxl345.c
+++ b/platform/z1/dev/adxl345.c
@@ -46,8 +46,10 @@
 #include "i2cmaster.h"
 
 /* Callback pointers when interrupt occurs */
-extern void (*accm_int1_cb)(u8_t reg);
-extern void (*accm_int2_cb)(u8_t reg);
+void (*accm_int1_cb)(u8_t reg);
+void (*accm_int2_cb)(u8_t reg);
+
+process_event_t int1_event, int2_event;
 
 /* Bitmasks for the interrupts */
 static uint16_t int1_mask = 0, int2_mask = 0;
diff --git a/platform/z1/dev/adxl345.h b/platform/z1/dev/adxl345.h
index 0eb80ccff..8da72cf5c 100644
--- a/platform/z1/dev/adxl345.h
+++ b/platform/z1/dev/adxl345.h
@@ -278,12 +278,12 @@ void    accm_set_irq(uint8_t int1, uint8_t int2);
 #define ADXL345_SRATE_0_10      0x00    // 0.10 Hz, when I2C data rate >= 100 kHz
 
 /* Callback pointers for the interrupts */
-void (*accm_int1_cb)(u8_t reg);
-void (*accm_int2_cb)(u8_t reg);
+extern void (*accm_int1_cb)(u8_t reg);
+extern void (*accm_int2_cb)(u8_t reg);
 
 /* Interrupt 1 and 2 events; ADXL345 signals interrupt on INT1 or INT2 pins,
   ISR is invoked and polls the accelerometer process which invokes the callbacks. */
-process_event_t int1_event, int2_event;   // static ?
+extern process_event_t int1_event, int2_event;   // static ?
 
 #define ACCM_INT1    0x01
 #define ACCM_INT2    0x02