--- a/devmem2.c
+++ b/devmem2.c
@@ -57,7 +57,7 @@
 
 int main(int argc, char **argv) {
     int fd;
-    void *map_base, *virt_addr; 
+    volatile void *map_base, *virt_addr; 
 	unsigned long read_result, writeval;
 	off_t target;
 	int access_type = 'w';
@@ -101,7 +101,7 @@ int main(int argc, char **argv) {
 			fprintf(stderr, "Illegal data type '%c'.\n", access_type);
 			exit(2);
 	}
-    printf("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result); 
+    printf("Value at address 0x%llX (%p): 0x%X\n", target, virt_addr, read_result); 
     fflush(stdout);
 
 	if(argc > 3) {