diff --git a/actionview/test/template/test_case_test.rb b/actionview/test/template/test_case_test.rb
index 5697ffa317..5ad1938b61 100644
--- a/actionview/test/template/test_case_test.rb
+++ b/actionview/test/template/test_case_test.rb
@@ -155,7 +155,7 @@ module ActionView
     test "view_assigns excludes internal ivars" do
       INTERNAL_IVARS.each do |ivar|
         assert defined?(ivar), "expected #{ivar} to be defined"
-        assert !view_assigns.keys.include?(ivar.to_s.sub('@', '').to_sym), "expected #{ivar} to be excluded from view_assigns"
+        assert !view_assigns.keys.include?(ivar.to_s.tr('@', '').to_sym), "expected #{ivar} to be excluded from view_assigns"
       end
     end
   end
diff --git a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
index 34a555dfd4..815e8eb97f 100644
--- a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
@@ -11,7 +11,7 @@ module ActiveRecord::Associations::Builder
         end
 
         def join_table
-          @join_table ||= [@lhs_class.table_name, klass.table_name].sort.join("\0").gsub(/^(.*[._])(.+)\0\1(.+)/, '\1\2_\3').gsub("\0", "_")
+          @join_table ||= [@lhs_class.table_name, klass.table_name].sort.join("\0").gsub(/^(.*[._])(.+)\0\1(.+)/, '\1\2_\3').tr("\0", "_")
         end
 
         private
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 171a6f4391..48e82d28d9 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -63,7 +63,7 @@ module ActiveRecord
     #   records, artists => artists_records
     #   music_artists, music_records => music_artists_records
     def self.derive_join_table_name(first_table, second_table) # :nodoc:
-      [first_table.to_s, second_table.to_s].sort.join("\0").gsub(/^(.*_)(.+)\0\1(.+)/, '\1\2_\3').gsub("\0", "_")
+      [first_table.to_s, second_table.to_s].sort.join("\0").gsub(/^(.*_)(.+)\0\1(.+)/, '\1\2_\3').tr("\0", "_")
     end
 
     module ClassMethods
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 49dfee96ec..55533a5d40 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -184,7 +184,7 @@ module ActiveSupport
     }
 
     UTC_OFFSET_WITH_COLON = '%s%02d:%02d'
-    UTC_OFFSET_WITHOUT_COLON = UTC_OFFSET_WITH_COLON.sub(':', '')
+    UTC_OFFSET_WITHOUT_COLON = UTC_OFFSET_WITH_COLON.tr(':', '')
 
     @lazy_zones_map = ThreadSafe::Cache.new