diff --git a/activesupport/lib/active_support/core_ext/date_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
index 9f0864d9bbc17cc6cbb517a3ae16fbe33660eda4..f347f092932c6e6b2bf9ba3f8dcf69c4b43f993f 100644
--- a/activesupport/lib/active_support/core_ext/date_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
@@ -1,3 +1,4 @@
+require 'date'
 require 'active_support/deprecation'
 
 class DateTime
diff --git a/activesupport/lib/active_support/core_ext/date_time/conversions.rb b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
index b7d8414a9d488556d0c576ca5eb7d12e6a029359..df07917d194a43b93b1416ec35c0589a3c4b4fb4 100644
--- a/activesupport/lib/active_support/core_ext/date_time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
@@ -1,3 +1,4 @@
+require 'date'
 require 'active_support/inflector/methods'
 require 'active_support/core_ext/time/conversions'
 require 'active_support/core_ext/date_time/calculations'
diff --git a/activesupport/lib/active_support/core_ext/date_time/zones.rb b/activesupport/lib/active_support/core_ext/date_time/zones.rb
index 6457ffbaf64bcea964aea08522fbfaf1609b4141..01a627f8afffb6314a17ef09d6df2abb801f898e 100644
--- a/activesupport/lib/active_support/core_ext/date_time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/zones.rb
@@ -1,3 +1,4 @@
+require 'date'
 require 'active_support/core_ext/time/zones'
 
 class DateTime