diff --git a/cpu/arm_common/arm_cpu.c b/cpu/arm_common/arm_cpu.c
index 032b42020d..0bf51b02ca 100644
--- a/cpu/arm_common/arm_cpu.c
+++ b/cpu/arm_common/arm_cpu.c
@@ -37,7 +37,7 @@ char *thread_stack_init(void (*task_func)(void), void *stack_start, int stack_si
 {
     unsigned int *stk;
     int i;
-    stk = (unsigned int *)(stack_start + stack_size);
+    stk = (unsigned int *)((unsigned int)stack_start + stack_size);
     stk--;
 
     *stk = STACK_MARKER;
@@ -48,7 +48,7 @@ char *thread_stack_init(void (*task_func)(void), void *stack_start, int stack_si
 
     /* set the stack pointer (SP) */
     stk--;
-    *stk = (unsigned int)(stack_start + stack_size) - 4;
+    *stk = (unsigned int)((unsigned int)stack_start + stack_size) - 4;
 
     /* build base stack */
     for (i = REGISTER_CNT; i >= 0 ; i--) {
diff --git a/cpu/lpc2387/mci/lpc2387-mci.c b/cpu/lpc2387/mci/lpc2387-mci.c
index 869e7081fc..b04aa3c341 100644
--- a/cpu/lpc2387/mci/lpc2387-mci.c
+++ b/cpu/lpc2387/mci/lpc2387-mci.c
@@ -879,7 +879,7 @@ DRESULT MCI_ioctl(
 )
 {
     DRESULT res;
-    unsigned char b, *ptr = buff;
+    unsigned char b, *ptr = (unsigned char *)buff;
     unsigned long resp[4], d, *dp, st, ed;
 
 
@@ -937,7 +937,7 @@ DRESULT MCI_ioctl(
                 break;    /* Check if sector erase can be applied to the card */
             }
 
-            dp = buff;
+            dp = (unsigned long *)buff;
             st = dp[0];
             ed = dp[1];
 
@@ -1000,7 +1000,7 @@ DRESULT MCI_ioctl(
                         while ((XferWp == 0) && !(XferStat & 0xC));
 
                         if (!(XferStat & 0xC)) {
-                            Copy_al2un(buff, DmaBuff[0], 64);
+                            Copy_al2un((unsigned char *)buff, DmaBuff[0], 64);
                             res = RES_OK;
                         }
                     }
diff --git a/cpu/native/native_cpu.c b/cpu/native/native_cpu.c
index e0dcaf8a66..7ac72aa5fa 100644
--- a/cpu/native/native_cpu.c
+++ b/cpu/native/native_cpu.c
@@ -78,7 +78,7 @@ char *thread_stack_init(void (*task_func)(void), void *stack_start, int stacksiz
 
     DEBUG("thread_stack_init()\n");
 
-    stk = stack_start;
+    stk = (unsigned int *)stack_start;
 
 #ifdef NATIVESPONTOP
     p = (ucontext_t *)stk;