diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 02aea8d21f..2a53fa95c1 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Fixed a compatibility issue with the `Oj` gem when cherry-picking the file
+    `active_support/core_ext/object/json` without requiring `active_support/json`.
+
+    Fixes #16131.
+
+    *Godfrey Chan*
+
 *   Make `Hash#with_indifferent_access` copy the default proc too.
 
     *arthurnn*, *Xanders*
diff --git a/activesupport/lib/active_support/core_ext/object/json.rb b/activesupport/lib/active_support/core_ext/object/json.rb
index 5496692373..698b2d1920 100644
--- a/activesupport/lib/active_support/core_ext/object/json.rb
+++ b/activesupport/lib/active_support/core_ext/object/json.rb
@@ -162,7 +162,7 @@ end
 
 class Time
   def as_json(options = nil) #:nodoc:
-    if ActiveSupport.use_standard_json_time_format
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
       xmlschema(ActiveSupport::JSON::Encoding.time_precision)
     else
       %(#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)})
@@ -172,7 +172,7 @@ end
 
 class Date
   def as_json(options = nil) #:nodoc:
-    if ActiveSupport.use_standard_json_time_format
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
       strftime("%Y-%m-%d")
     else
       strftime("%Y/%m/%d")
@@ -182,7 +182,7 @@ end
 
 class DateTime
   def as_json(options = nil) #:nodoc:
-    if ActiveSupport.use_standard_json_time_format
+    if ActiveSupport::JSON::Encoding.use_standard_json_time_format
       xmlschema(ActiveSupport::JSON::Encoding.time_precision)
     else
       strftime('%Y/%m/%d %H:%M:%S %z')