diff --git a/foreign/c/pointer.scm b/foreign/c/pointer.scm
index 25013a9..8b8040b 100644
--- a/foreign/c/pointer.scm
+++ b/foreign/c/pointer.scm
@@ -100,13 +100,14 @@
   (chicken #t) ; FIXME
   (kawa #t) ; FIXME
   (chibi #t)
+  (gauche (define c-null? pointer-null?))
   (else (define c-null?
           (lambda (pointer)
             (display "HERE123: ")
             (write pointer)
             (newline)
             (if (c-bytevector? pointer)
-              #t ;(= (c-memset-pointer->address pointer 0 0) 0)
+              #t (= (c-memset-pointer->address pointer 0 0) 0)
               #f)))))
 
 #;(define c-bytevector->address
diff --git a/foreign/c/primitives/gauche.scm b/foreign/c/primitives/gauche.scm
index 40eb509..8b2a0c4 100644
--- a/foreign/c/primitives/gauche.scm
+++ b/foreign/c/primitives/gauche.scm
@@ -6,7 +6,7 @@
                        c-bytevector-pointer-set!
                        c-bytevector-pointer-ref
                        ;pointer-null
-                       ;pointer-null?
+                       pointer-null?
                        ;make-c-bytevector
                        ;pointer-address
                        c-bytevector?
@@ -17,8 +17,7 @@
                        define-c-callback
                        dlerror
                        dlsym
-                       internal-ffi-call
-                       ))
+                       internal-ffi-call))
 
 (select-module foreign.c.primitives.gauche)
 (dynamic-load "foreign/c/lib/gauche")
diff --git a/foreign/c/primitives/gauche/foreign-c-primitives-gauche.c b/foreign/c/primitives/gauche/foreign-c-primitives-gauche.c
index 285a2e0..efd3d6e 100644
--- a/foreign/c/primitives/gauche/foreign-c-primitives-gauche.c
+++ b/foreign/c/primitives/gauche/foreign-c-primitives-gauche.c
@@ -60,7 +60,6 @@ ScmObj pointer_null() {
 }
 */
 
-/*
 ScmObj is_pointer_null(ScmObj pointer) {
     if(!Scm_TypeP(pointer, SCM_CLASS_FOREIGN_POINTER)) {
         return SCM_FALSE;
@@ -71,7 +70,6 @@ ScmObj is_pointer_null(ScmObj pointer) {
         return SCM_FALSE;
     }
 }
-*/
 
 /*
 ScmObj pointer_allocate(int size) {
diff --git a/foreign/c/primitives/gauche/foreign-c-primitives-gauche.h b/foreign/c/primitives/gauche/foreign-c-primitives-gauche.h
index bb0918b..ed6ffe2 100644
--- a/foreign/c/primitives/gauche/foreign-c-primitives-gauche.h
+++ b/foreign/c/primitives/gauche/foreign-c-primitives-gauche.h
@@ -21,7 +21,7 @@ extern ScmObj size_of_pointer();
 extern ScmObj size_of_void();
 extern ScmObj shared_object_load(ScmString* path, ScmObj options);
 //extern ScmObj pointer_null();
-//extern ScmObj is_pointer_null();
+extern ScmObj is_pointer_null();
 //extern ScmObj pointer_allocate(int size);
 //extern ScmObj pointer_address(ScmObj pointer);
 extern ScmObj is_pointer(ScmObj pointer);
diff --git a/foreign/c/primitives/gauche/gauchelib.scm b/foreign/c/primitives/gauche/gauchelib.scm
index 8e5fdc1..b07269f 100644
--- a/foreign/c/primitives/gauche/gauchelib.scm
+++ b/foreign/c/primitives/gauche/gauchelib.scm
@@ -25,7 +25,7 @@
  (define-cproc size-of-void () size_of_void)
  (define-cproc shared-object-load (path::<string> options) shared_object_load)
  ;(define-cproc pointer-null () pointer_null)
- ;(define-cproc pointer-null? (pointer) is_pointer_null)
+ (define-cproc pointer-null? (pointer) is_pointer_null)
  ;(define-cproc pointer-allocate (size::<int>) pointer_allocate)
  ;(define-cproc pointer-address (object) pointer_address)
  (define-cproc pointer? (pointer) is_pointer)