1 files changed, 13 insertions, 2 deletions
diff --git a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
index 3720dbb8b8..080604147d 100644
--- a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
@@ -1,23 +1,34 @@
 require 'bigdecimal'
+
+begin
+  require 'psych'
+rescue LoadError
+end
+
 require 'yaml'
 
 class BigDecimal
   YAML_TAG = 'tag:yaml.org,2002:float'
   YAML_MAPPING = { 'Infinity' => '.Inf', '-Infinity' => '-.Inf', 'NaN' => '.NaN' }
 
-  yaml_as YAML_TAG
-
   # This emits the number without any scientific notation.
   # This is better than self.to_f.to_s since it doesn't lose precision.
   #
   # Note that reconstituting YAML floats to native floats may lose precision.
   def to_yaml(opts = {})
+    return super if defined?(YAML::ENGINE) && !YAML::ENGINE.syck?
+
     YAML.quick_emit(nil, opts) do |out|
       string = to_s
       out.scalar(YAML_TAG, YAML_MAPPING[string] || string, :plain)
     end
   end
 
+  def encode_with(coder)
+    string = to_s
+    coder.represent_scalar(nil, YAML_MAPPING[string] || string)
+  end
+
   def to_d
     self
   end