diff --git a/actioncable/lib/action_cable/subscription_adapter/postgresql.rb b/actioncable/lib/action_cable/subscription_adapter/postgresql.rb
index a9c09499503d32192135b918ad245564ba02140d..e384ea4afbbd46dd7222634b06302ffd225f32c3 100644
--- a/actioncable/lib/action_cable/subscription_adapter/postgresql.rb
+++ b/actioncable/lib/action_cable/subscription_adapter/postgresql.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-gem "pg", "~> 0.18"
+gem "pg", ">= 0.18", "< 2.0"
 require "pg"
 require "thread"
 require "digest/sha1"
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 441be47fa18aa2f2378c6683282fe4a0035f914c..9ac5a8760e0bc18322c60202c11543affee98cee 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 # Make sure we're using pg high enough for type casts and Ruby 2.2+ compatibility
-gem "pg", "~> 0.18"
+gem "pg", ">= 0.18", "< 2.0"
 require "pg"
 
 require "active_record/connection_adapters/abstract_adapter"
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index e18aeda0d05ddb4f7660843b7143ce91d9cb73a0..e152a95fd37d3f316e6e01d32e890c3e0e1d670c 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -301,7 +301,7 @@ def gem_for_database
         # %w( mysql postgresql sqlite3 oracle frontbase ibm_db sqlserver jdbcmysql jdbcsqlite3 jdbcpostgresql )
         case options[:database]
         when "mysql"          then ["mysql2", ["~> 0.4.4"]]
-        when "postgresql"     then ["pg", ["~> 0.18"]]
+        when "postgresql"     then ["pg", [">= 0.18", "< 2.0"]]
         when "oracle"         then ["activerecord-oracle_enhanced-adapter", nil]
         when "frontbase"      then ["ruby-frontbase", nil]
         when "sqlserver"      then ["activerecord-sqlserver-adapter", nil]
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index 3f01da42fb24c3481413e0506cbbdfa1763f4baf..60b9ff13176792c69373a6f043f57f04a9f1495b 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -413,7 +413,7 @@ def test_config_postgresql_database
     if defined?(JRUBY_VERSION)
       assert_gem "activerecord-jdbcpostgresql-adapter"
     else
-      assert_gem "pg", "'~> 0.18'"
+      assert_gem "pg", "'>= 0.18', '< 2.0'"
     end
   end