diff --git a/retropikzel/pffi/chibi.scm b/retropikzel/pffi/chibi.scm
index 91e0918..2c88779 100644
--- a/retropikzel/pffi/chibi.scm
+++ b/retropikzel/pffi/chibi.scm
@@ -183,12 +183,6 @@
                               (if (equal? return-type 'void)
                                 0
                                 (size-of-type return-type)))))
-          (display "Calling function: ")
-          (display c-name)
-          (newline)
-          (display "With arguments: ")
-          (display arguments)
-          (newline)
           (internal-ffi-call (length argument-types)
                              (pffi-type->libffi-type return-type)
                              (map pffi-type->libffi-type argument-types)
@@ -198,12 +192,6 @@
                                   arguments
                                   argument-types))
           (cond ((not (equal? return-type 'void))
-                 (display "Return value pointer: ")
-                 (write return-value)
-                 (newline)
-                 (display "Return value: ")
-                 (write (pffi-pointer-get return-value return-type 0))
-                 (newline)
                  (pffi-pointer-get return-value return-type 0))))))))
 
 (define-syntax pffi-define
diff --git a/retropikzel/pffi/gauche.scm b/retropikzel/pffi/gauche.scm
index 78bf1c8..9e840eb 100644
--- a/retropikzel/pffi/gauche.scm
+++ b/retropikzel/pffi/gauche.scm
@@ -148,8 +148,7 @@
 
 (define argument->pointer
   (lambda (value type)
-    (cond ;((pffi-pointer? value) value)
-          ((procedure? value) (scheme-procedure-to-pointer value))
+    (cond ((procedure? value) (scheme-procedure-to-pointer value))
           (else (let ((pointer (pffi-pointer-allocate (size-of-type type))))
                   (pffi-pointer-set! pointer type 0 value)
                   pointer)))))
@@ -166,23 +165,6 @@
                               (if (equal? return-type 'void)
                                 0
                                 (size-of-type return-type)))))
-          (display "Calling function: ")
-          (display c-name)
-          (newline)
-          (display "Return type: ")
-          (write (pffi-type->libffi-type return-type))
-          (newline)
-          (display "Argument types: ")
-          (write (map pffi-type->libffi-type argument-types))
-          (newline)
-          (display "Size of return type: ")
-          (write (size-of-type return-type))
-          (newline)
-          (display "Argument pointers: ")
-          (write (map argument->pointer
-                      arguments
-                      argument-types))
-          (newline)
           (internal-ffi-call (length argument-types)
                              (pffi-type->libffi-type return-type)
                              (map pffi-type->libffi-type argument-types)
@@ -191,13 +173,7 @@
                              (map argument->pointer
                                   arguments
                                   argument-types))
-          (display "Return value pointer: ")
-          (write return-value)
-          (newline)
           (cond ((not (equal? return-type 'void))
-                 (display "Return value: ")
-                 (write (pffi-pointer-get return-value return-type 0))
-                 (newline)
                  (pffi-pointer-get return-value return-type 0))))))))
 
 (define-syntax pffi-define
diff --git a/src/gauche/pffi.c b/src/gauche/pffi.c
index 6c80808..5dd32da 100644
--- a/src/gauche/pffi.c
+++ b/src/gauche/pffi.c
@@ -507,7 +507,6 @@ ScmObj pointer_to_string(ScmObj pointer) {
     if(SCM_FOREIGN_POINTER_P(pointer)) {
         void* p = SCM_FOREIGN_POINTER_REF(void*, pointer);
         void* string = (char*)p;
-        printf("Pointer to string: %s\n", string);
         return Scm_MakeString(string, -1, -1, 0);
     } else {
         Scm_Error("Not a pointer: %S", pointer);
@@ -666,25 +665,10 @@ ScmObj internal_ffi_call(ScmObj nargs, ScmObj rtype, ScmObj atypes, ScmObj fn, S
     for(int i = 0; i < avalues_length; i++) {
         ScmObj item = Scm_ListRef(avalues, i, SCM_UNDEFINED);
         void* pp = SCM_FOREIGN_POINTER_REF(void*, item);
-        printf("DEBUG1: %i\n", i);
         char* list_p = (char*)c_avalues + (sizeof(void) * i);
-        /*
-        if(c_atypes[i] == &ffi_type_pointer) {
-            c_avalues[i] = &pp;
-            printf("DEBUG2: %i\n", &c_avalues[i]);
-            printf("DEBUG2.1: %i\n", &pp);
-        } else {
-            printf("DEBUG2: %i\n", *(int*)pp);
-            c_avalues[i] = pp;
-        }
-        */
         c_avalues[i] = pp;
     }
-    printf("HERE2\n");
-    printf("DEBUG3.1: %i\n", &c_rvalue);
     ffi_call(&cif, FFI_FN(c_fn), c_rvalue, c_avalues);
-    printf("DEBUG3.2: %i\n", &c_rvalue);
-    printf("HERE3\n");
 
     return SCM_UNDEFINED;
 }