return NULL;
 }
 
-int watchpoint_add(target_t *target, uint32_t address, uint32_t length, enum watchpoint_rw rw, uint32_t value, uint32_t mask)
+int watchpoint_add(target_t *target, uint32_t address, uint32_t length,
+               enum watchpoint_rw rw, uint32_t value, uint32_t mask)
 {
        watchpoint_t *watchpoint = target->watchpoints;
        watchpoint_t **watchpoint_p = &target->watchpoints;
        int retval;
+       char *reason;
 
        while (watchpoint)
        {
-               if (watchpoint->address == address)
+               if (watchpoint->address == address) {
+                       if (watchpoint->length != length
+                                       || watchpoint->value != value
+                                       || watchpoint->mask != mask
+                                       || watchpoint->rw != rw) {
+                               LOG_ERROR("address 0x%8.8" PRIx32
+                                               "already has watchpoint %d",
+                                               address, watchpoint->unique_id);
+                               return ERROR_FAIL;
+                       }
+
+                       /* ignore duplicate watchpoint */
                        return ERROR_OK;
+               }
                watchpoint_p = &watchpoint->next;
                watchpoint = watchpoint->next;
        }
 
-       (*watchpoint_p) = malloc(sizeof(watchpoint_t));
+       (*watchpoint_p) = calloc(1, sizeof(watchpoint_t));
        (*watchpoint_p)->address = address;
        (*watchpoint_p)->length = length;
        (*watchpoint_p)->value = value;
        (*watchpoint_p)->mask = mask;
        (*watchpoint_p)->rw = rw;
-       (*watchpoint_p)->set = 0;
-       (*watchpoint_p)->next = NULL;
        (*watchpoint_p)->unique_id = bpwp_unique_id++;
 
-       if ((retval = target_add_watchpoint(target, *watchpoint_p)) != ERROR_OK)
-       {
-               switch (retval)
-               {
-                       case ERROR_TARGET_RESOURCE_NOT_AVAILABLE:
-                               LOG_INFO("can't add %s watchpoint, resource not available (WPID: %d)",
-                                        watchpoint_rw_strings[(*watchpoint_p)->rw],
-                                        (*watchpoint_p)->unique_id );
-                               free (*watchpoint_p);
-                               *watchpoint_p = NULL;
-                               return retval;
-                               break;
-                       case ERROR_TARGET_NOT_HALTED:
-                               LOG_INFO("can't add watchpoint while target is running (WPID: %d)",
-                                                (*watchpoint_p)->unique_id );
-                               free (*watchpoint_p);
-                               *watchpoint_p = NULL;
-                               return retval;
-                               break;
-                       default:
-                               LOG_ERROR("unknown error");
-                               exit(-1);
-                               break;
-               }
+       retval = target_add_watchpoint(target, *watchpoint_p);
+       switch (retval) {
+       case ERROR_OK:
+               break;
+       case ERROR_TARGET_RESOURCE_NOT_AVAILABLE:
+               reason = "resource not available";
+               goto bye;
+       case ERROR_TARGET_NOT_HALTED:
+               reason = "target running";
+               goto bye;
+       default:
+               reason = "unrecognized error";
+bye:
+               LOG_ERROR("can't add %s watchpoint at 0x%8.8" PRIx32 ", %s",
+                        watchpoint_rw_strings[(*watchpoint_p)->rw],
+                        address, reason);
+               free (*watchpoint_p);
+               *watchpoint_p = NULL;
+               return retval;
        }
 
        LOG_DEBUG("added %s watchpoint at 0x%8.8" PRIx32 " of length 0x%8.8x (WPID: %d)",