diff --git a/flash.h b/flash.h
index 9e787c0..cba7bd8 100644
--- a/flash.h
+++ b/flash.h
@@ -43,10 +43,10 @@
 
 /* TODO: check using code for correct usage of types */
 typedef uintptr_t chipaddr;
+#define PRIxPTR_WIDTH ((int)(sizeof(uintptr_t)*2))
 
 int register_shutdown(int (*function) (void *data), void *data);
-void *programmer_map_flash_region(const char *descr, unsigned long phys_addr,
-				  size_t len);
+void *programmer_map_flash_region(const char *descr, uintptr_t phys_addr, size_t len);
 void programmer_unmap_flash_region(void *virt_addr, size_t len);
 void programmer_delay(int usecs);