diff --git a/active_record_union.gemspec b/active_record_union.gemspec
index 95cdd34..a945f75 100644
--- a/active_record_union.gemspec
+++ b/active_record_union.gemspec
@@ -24,7 +24,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec",   "~> 3.0"
   spec.add_development_dependency "pry"
-  spec.add_development_dependency "sqlite3"
-  spec.add_development_dependency "pg"
   spec.add_development_dependency "mysql2"
 end
diff --git a/rails_5_0.gemfile b/rails_5_0.gemfile
index 4c77ac2..accec1f 100644
--- a/rails_5_0.gemfile
+++ b/rails_5_0.gemfile
@@ -10,4 +10,4 @@ gem 'rails', '~> 5.0.0'
 # https://bitbucket.org/ged/ruby-pg/issues/270/pg-100-x64-mingw32-rails-server-not-start
 gem 'pg', '~> 0.21'
 
-gem 'sqlite3'
+gem 'sqlite3', '~> 1.3.6'
diff --git a/rails_5_1.gemfile b/rails_5_1.gemfile
index 0a9e6bd..3a6d91f 100644
--- a/rails_5_1.gemfile
+++ b/rails_5_1.gemfile
@@ -10,4 +10,4 @@ gem 'rails', '~> 5.1.0'
 # https://bitbucket.org/ged/ruby-pg/issues/270/pg-100-x64-mingw32-rails-server-not-start
 gem 'pg', '~> 0.21'
 
-gem 'sqlite3'
+gem 'sqlite3', '~> 1.4.0'
diff --git a/rails_5_2.gemfile b/rails_5_2.gemfile
index ab0cc7f..e6b73e3 100644
--- a/rails_5_2.gemfile
+++ b/rails_5_2.gemfile
@@ -3,9 +3,8 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in active_record_union.gemspec
 gemspec
 
-# pg v1.0+ compatibility, https://github.com/rails/rails/pull/31671:
 gem 'rails', '~> 5.2.0'
 
 gem 'pg'
 
-gem 'sqlite3'
+gem 'sqlite3', '~> 1.4.0'