diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 05568039d8..627e93b5b6 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -1,4 +1,5 @@
 require "set"
+require "zlib"
 require "active_support/core_ext/module/attribute_accessors"
 require "active_support/core_ext/regexp"