diff --git a/ext/cbson/cbson.c b/ext/cbson/cbson.c
index 37708cc..b29c013 100644
--- a/ext/cbson/cbson.c
+++ b/ext/cbson/cbson.c
@@ -151,6 +151,10 @@ static int write_element_allow_id(VALUE key, VALUE value, VALUE extra, int allow
     switch(TYPE(value)) {
     case T_BIGNUM:
         {
+            if (rb_funcall(value, rb_intern(">"), 1, INT2NUM(2147483647)) == Qtrue ||
+                rb_funcall(value, rb_intern("<"), 1, INT2NUM(-2147483648)) == Qtrue) {
+                rb_raise(rb_eRangeError, "MongoDB can only handle 4-byte ints - try converting to a double before saving");
+            }
             write_name_and_type(buffer, key, 0x10);
             VALUE as_f = rb_funcall(value, rb_intern("to_f"), 0);
             int int_value = NUM2LL(as_f);
diff --git a/lib/mongo/util/bson.rb b/lib/mongo/util/bson.rb
index 91d9e07..a4acd43 100644
--- a/lib/mongo/util/bson.rb
+++ b/lib/mongo/util/bson.rb
@@ -248,7 +248,10 @@ class BSON
   end
 
   def deserialize_number_int_data(buf)
-    buf.get_int
+    # sometimes ruby makes me angry... why would the same code pack as signed
+    # but unpack as unsigned
+    unsigned = buf.get_int
+    unsigned >= 2**32 / 2 ? unsigned - 2**32 : unsigned
   end
 
   def deserialize_object_data(buf)
@@ -387,6 +390,9 @@ class BSON
     if type == NUMBER
       buf.put_double(val)
     else
+      if val > 2**32 / 2 - 1 or val < -2**32 / 2
+        raise RangeError.new "MongoDB can only handle 4-byte ints - try converting to a double before saving"
+      end
       buf.put_int(val)
     end
   end
diff --git a/tests/test_bson.rb b/tests/test_bson.rb
index be67a1b..e2b318c 100644
--- a/tests/test_bson.rb
+++ b/tests/test_bson.rb
@@ -36,6 +36,18 @@ class BSONTest < Test::Unit::TestCase
     doc = {'doc' => 42}
     @b.serialize(doc)
     assert_equal doc, @b.deserialize
+
+    doc = {"doc" => -5600}
+    @b.serialize(doc)
+    assert_equal doc, @b.deserialize
+
+    doc = {"doc" => 2147483647}
+    @b.serialize(doc)
+    assert_equal doc, @b.deserialize
+
+    doc = {"doc" => -2147483648}
+    @b.serialize(doc)
+    assert_equal doc, @b.deserialize
   end
 
   def test_ordered_hash
@@ -195,6 +207,21 @@ class BSONTest < Test::Unit::TestCase
                                       0x00, 0x00, 0x00])
   end
 
+  def test_overflow
+    doc = {"x" => 2**45}
+    assert_raise RangeError do
+      @b.serialize(doc)
+    end
+
+    doc = {"x" => 2147483647}
+    assert_equal doc, @b.deserialize(@b.serialize(doc).to_a)
+
+    doc["x"] = doc["x"] + 1
+    assert_raise RangeError do
+      @b.serialize(doc)
+    end
+  end
+
   def test_do_not_change_original_object
     val = OrderedHash.new
     val['not_id'] = 1