diff --git a/ChangeLog b/ChangeLog
index b8372656d9..cd315e4c63 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Tue Jul 22 20:42:24 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimalCmp): BigDecimal#<=> should
+	  return nil if an argument can't be coerced into BigDecimal.
+
+	* ext/bigdecimal/bigdecimal.h, ext/bigdecimal/bigdecimal.c
+	  (VpIsNegDoubleZero, VpItoV): comment out unused functions.
+
 Tue Jul 22 20:33:54 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* test/rdoc/test_rdoc_parser_ruby.rb (teardown): close tempfile.
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 013293365c..614032953c 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -730,11 +730,11 @@ BigDecimalCmp(VALUE self, VALUE r,char op)
     GUARD_OBJ(a,GetVpValue(self,1));
     b = GetVpValue(r,0);
     if(!b) {
-	ID f;
+	ID f = 0;
 
 	switch(op)
 	{
-	  case '*': return   INT2FIX(e); /* any op */
+	  case '*': return Qnil; /* any op */
 	  case '=': f = rb_intern("=="); break;
 	  case '!': f = rb_intern("!="); break;
 	  case 'G': f = rb_intern(">="); break;
@@ -2196,12 +2196,14 @@ VpGetDoubleNegZero(void) /* Returns the value of -0 */
     return nzero;
 }
 
+#if 0  /* unused */
 VP_EXPORT int
 VpIsNegDoubleZero(double v)
 {
     double z = VpGetDoubleNegZero();
     return MemCmp(&v,&z,sizeof(v))==0;
 }
+#endif
 
 VP_EXPORT int
 VpException(unsigned short f, const char *str,int always)
@@ -4173,6 +4175,7 @@ Exit:
 /*
  *  m <- ival
  */
+#if 0  /* unused */
 VP_EXPORT void
 VpItoV(Real *m, S_INT ival)
 {
@@ -4230,6 +4233,7 @@ Exit:
 #endif /* _DEBUG */
     return;
 }
+#endif
 
 /*
  * y = SQRT(x),  y*y - x =>0
diff --git a/ext/bigdecimal/bigdecimal.h b/ext/bigdecimal/bigdecimal.h
index 4f77feab00..3a300f1df5 100644
--- a/ext/bigdecimal/bigdecimal.h
+++ b/ext/bigdecimal/bigdecimal.h
@@ -127,7 +127,9 @@ VP_EXPORT unsigned long VpGetRoundMode(void);
 VP_EXPORT unsigned long VpSetRoundMode(unsigned long n);
 
 VP_EXPORT int VpException(unsigned short f,const char *str,int always);
+#if 0  /* unused */
 VP_EXPORT int VpIsNegDoubleZero(double v);
+#endif
 VP_EXPORT U_LONG VpNumOfChars(Real *vp,const char *pszFmt);
 VP_EXPORT U_LONG VpInit(U_LONG BaseVal);
 VP_EXPORT void *VpMemAlloc(U_LONG mb);
@@ -146,7 +148,9 @@ VP_EXPORT void VpToFString(Real *a,char *psz,int fFmt,int fPlus);
 VP_EXPORT int VpCtoV(Real *a,const char *int_chr,U_LONG ni,const char *frac,U_LONG nf,const char *exp_chr,U_LONG ne);
 VP_EXPORT int VpVtoD(double *d,S_LONG *e,Real *m);
 VP_EXPORT void VpDtoV(Real *m,double d);
+#if 0  /* unused */
 VP_EXPORT void VpItoV(Real *m,S_INT ival);
+#endif
 VP_EXPORT int VpSqrt(Real *y,Real *x);
 VP_EXPORT int VpActiveRound(Real *y,Real *x,int f,int il);
 VP_EXPORT int VpMidRound(Real *y, int f, int nf);