diff --git a/lib/plsql/oci_connection.rb b/lib/plsql/oci_connection.rb
index a74cd9d8..cd998c6d 100644
--- a/lib/plsql/oci_connection.rb
+++ b/lib/plsql/oci_connection.rb
@@ -68,14 +68,16 @@ def exec(sql, *bindvars)
     class Cursor #:nodoc:
       include Connection::CursorCommon
 
-      # stack of open cursors
-      @@open_cursors = []
+      # stacks of open cursors (for each thread)
+      def self.open_cursors(thread_id = Thread.current.object_id)
+        (@@open_cursors ||= Hash.new {|stacks, id| stacks[id] = []})[thread_id]
+      end
       attr_reader :raw_cursor
 
       def initialize(conn, raw_cursor)
         @connection = conn
         @raw_cursor = raw_cursor
-        @@open_cursors.push self
+        self.class.open_cursors.push self
       end
 
       def self.new_from_parse(conn, sql)
@@ -125,7 +127,7 @@ def close_raw_cursor
 
       def close
         # close all cursors that were created after this one
-        while (open_cursor = @@open_cursors.pop) && !open_cursor.equal?(self)
+        while (open_cursor = self.class.open_cursors.pop) && !open_cursor.equal?(self)
           open_cursor.close_raw_cursor
         end
         close_raw_cursor
diff --git a/spec/plsql/schema_spec.rb b/spec/plsql/schema_spec.rb
index f4bd2eca..9743d5f2 100644
--- a/spec/plsql/schema_spec.rb
+++ b/spec/plsql/schema_spec.rb
@@ -219,6 +219,15 @@ class TestModel < TestBaseModel
     plsql.activerecord_class = TestModel
     plsql.schema_name.should == 'HR'
   end
+
+  it "should safely close cursors in threaded environment" do
+    unless defined?(JRuby)
+      t1 = Thread.new {plsql.dbms_lock.sleep(1)}.tap {|t| t.abort_on_exception = true}
+      t2 = Thread.new {plsql.dbms_lock.sleep(2)}.tap {|t| t.abort_on_exception = true}
+      t2.join
+    end
+  end
+
 end if defined?(ActiveRecord)
 
 describe "DBMS_OUTPUT logging" do