diff --git a/ChangeLog b/ChangeLog
index 7d919d23a7..dc3abec798 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+Sun Jan 13 15:00:00 2013  Kenta Murata  <mrkn@mrkn.jp>
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_sub):
+	  need to specify precision for converting Rational and Float.
+	  [ruby-dev:46544] [Bug #7404]
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_mult): ditto.
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_divide): ditto.
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_DoDivmod): ditto.
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_divremain): ditto.
+
+	* test/bigdecimal/test_bigdecimal.rb: add tests for the above fixes.
+
 Sun Jan 13 14:48:55 2013  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
 
 	* lib/matrix/eigenvalue_decomposition: Fix eigensystem with complex
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 7cd0044532..dca54b44db 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -894,7 +894,16 @@ BigDecimal_sub(VALUE self, VALUE r)
     size_t mx;
 
     GUARD_OBJ(a,GetVpValue(self,1));
-    b = GetVpValue(r,0);
+    if (TYPE(r) == T_FLOAT) {
+	b = GetVpValueWithPrec(r, DBL_DIG+1, 1);
+    }
+    else if (TYPE(r) == T_RATIONAL) {
+	b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1);
+    }
+    else {
+	b = GetVpValue(r,0);
+    }
+
     if(!b) return DoSomeOne(self,r,'-');
     SAVE(b);
 
@@ -1146,7 +1155,16 @@ BigDecimal_mult(VALUE self, VALUE r)
     size_t mx;
 
     GUARD_OBJ(a,GetVpValue(self,1));
-    b = GetVpValue(r,0);
+    if (TYPE(r) == T_FLOAT) {
+	b = GetVpValueWithPrec(r, DBL_DIG+1, 1);
+    }
+    else if (TYPE(r) == T_RATIONAL) {
+	b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1);
+    }
+    else {
+	b = GetVpValue(r,0);
+    }
+
     if(!b) return DoSomeOne(self,r,'*');
     SAVE(b);
 
@@ -1165,9 +1183,19 @@ BigDecimal_divide(Real **c, Real **res, Real **div, VALUE self, VALUE r)
     size_t mx;
 
     GUARD_OBJ(a,GetVpValue(self,1));
-    b = GetVpValue(r,0);
+    if (TYPE(r) == T_FLOAT) {
+	b = GetVpValueWithPrec(r, DBL_DIG+1, 1);
+    }
+    else if (TYPE(r) == T_RATIONAL) {
+	b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1);
+    }
+    else {
+	b = GetVpValue(r,0);
+    }
+
     if(!b) return DoSomeOne(self,r,'/');
     SAVE(b);
+
     *div = b;
     mx = a->Prec + vabs(a->exponent);
     if(mx<b->Prec + vabs(b->exponent)) mx = b->Prec + vabs(b->exponent);
@@ -1230,7 +1258,16 @@ BigDecimal_DoDivmod(VALUE self, VALUE r, Real **div, Real **mod)
     size_t mx;
 
     GUARD_OBJ(a,GetVpValue(self,1));
-    b = GetVpValue(r,0);
+    if (TYPE(r) == T_FLOAT) {
+	b = GetVpValueWithPrec(r, DBL_DIG+1, 1);
+    }
+    else if (TYPE(r) == T_RATIONAL) {
+	b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1);
+    }
+    else {
+	b = GetVpValue(r,0);
+    }
+
     if(!b) return Qfalse;
     SAVE(b);
 
@@ -1322,7 +1359,16 @@ BigDecimal_divremain(VALUE self, VALUE r, Real **dv, Real **rv)
     Real *f=NULL;
 
     GUARD_OBJ(a,GetVpValue(self,1));
-    b = GetVpValue(r,0);
+    if (TYPE(r) == T_FLOAT) {
+	b = GetVpValueWithPrec(r, DBL_DIG+1, 1);
+    }
+    else if (TYPE(r) == T_RATIONAL) {
+	b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1);
+    }
+    else {
+	b = GetVpValue(r,0);
+    }
+
     if(!b) return DoSomeOne(self,r,rb_intern("remainder"));
     SAVE(b);
 
diff --git a/test/bigdecimal/test_bigdecimal.rb b/test/bigdecimal/test_bigdecimal.rb
index 51d2e8f309..07c79a8874 100644
--- a/test/bigdecimal/test_bigdecimal.rb
+++ b/test/bigdecimal/test_bigdecimal.rb
@@ -652,6 +652,14 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(BigDecimal.new((2**100-1).to_s), x - 1)
   end
 
+  def test_sub_with_float
+    assert_kind_of(BigDecimal, BigDecimal.new("3") - 1.0)
+  end
+
+  def test_sub_with_rational
+    assert_kind_of(BigDecimal, BigDecimal.new("3") - 1.quo(3))
+  end
+
   def test_mult
     x = BigDecimal.new((2**100).to_s)
     assert_equal(BigDecimal.new((2**100 * 3).to_s), (x * 3).to_i)
@@ -660,6 +668,14 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(BigDecimal.new((2**200).to_s), (x * x).to_i)
   end
 
+  def test_mult_with_float
+    assert_kind_of(BigDecimal, BigDecimal.new("3") * 1.5)
+  end
+
+  def test_mult_with_rational
+    assert_kind_of(BigDecimal, BigDecimal.new("3") * 1.quo(3))
+  end
+
   def test_div
     x = BigDecimal.new((2**100).to_s)
     assert_equal(BigDecimal.new((2**100 / 3).to_s), (x / 3).to_i)
@@ -669,6 +685,14 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(-2, BigDecimal.new("2") / -1)
   end
 
+  def test_div_with_float
+    assert_kind_of(BigDecimal, BigDecimal.new("3") / 1.5)
+  end
+
+  def test_div_with_rational
+    assert_kind_of(BigDecimal, BigDecimal.new("3") / 1.quo(3))
+  end
+
   def test_mod
     x = BigDecimal.new((2**100).to_s)
     assert_equal(1, x % 3)
@@ -677,6 +701,14 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(-1, (-x) % -3)
   end
 
+  def test_mod_with_float
+    assert_kind_of(BigDecimal, BigDecimal.new("3") % 1.5)
+  end
+
+  def test_mod_with_rational
+    assert_kind_of(BigDecimal, BigDecimal.new("3") % 1.quo(3))
+  end
+
   def test_remainder
     x = BigDecimal.new((2**100).to_s)
     assert_equal(1, x.remainder(3))
@@ -685,6 +717,14 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(-1, (-x).remainder(-3))
   end
 
+  def test_remainder_with_float
+    assert_kind_of(BigDecimal, BigDecimal.new("3").remainder(1.5))
+  end
+
+  def test_remainder_with_rational
+    assert_kind_of(BigDecimal, BigDecimal.new("3").remainder(1.quo(3)))
+  end
+
   def test_divmod
     x = BigDecimal.new((2**100).to_s)
     assert_equal([(x / 3).floor, 1], x.divmod(3))