diff --git a/Gemfile b/Gemfile
index a1585e279c9..1d9685412f5 100644
--- a/Gemfile
+++ b/Gemfile
@@ -99,3 +99,6 @@ if ENV['ORACLE_ENHANCED_PATH'] || ENV['ORACLE_ENHANCED']
     gem "activerecord-oracle_enhanced-adapter", :git => "git://github.com/rsim/oracle-enhanced.git"
   end
 end
+
+# A gem necessary for ActiveRecord tests with Oracle database
+gem "ibm_db" if ENV['IBM_DB']
diff --git a/activerecord/test/config.example.yml b/activerecord/test/config.example.yml
index 8c1a45430e8..f450efd8390 100644
--- a/activerecord/test/config.example.yml
+++ b/activerecord/test/config.example.yml
@@ -37,11 +37,13 @@ connections:
 
   db2:
     arunit:
+      adapter:  ibm_db
       host:     localhost
       username: arunit
       password: arunit
       database: arunit
     arunit2:
+      adapter:  ibm_db
       host:     localhost
       username: arunit
       password: arunit