diff --git a/lib/plsql/oci_connection.rb b/lib/plsql/oci_connection.rb
index a74cd9d8..99e9ec64 100644
--- a/lib/plsql/oci_connection.rb
+++ b/lib/plsql/oci_connection.rb
@@ -68,14 +68,17 @@ def exec(sql, *bindvars)
     class Cursor #:nodoc:
       include Connection::CursorCommon
 
-      # stack of open cursors
-      @@open_cursors = []
       attr_reader :raw_cursor
 
+      # stack of open cursors per thread
+      def self.open_cursors
+        Thread.current[:plsql_oci_cursor_stack] ||= []
+      end
+
       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 +128,7 @@ 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
@@ -336,4 +339,4 @@ def ora_date_to_ruby_date(val)
 
   end
   
-end
\ No newline at end of file
+end
diff --git a/spec/plsql/schema_spec.rb b/spec/plsql/schema_spec.rb
index ff335533..2ff7238b 100644
--- a/spec/plsql/schema_spec.rb
+++ b/spec/plsql/schema_spec.rb
@@ -220,6 +220,15 @@ class TestModel < TestBaseModel
     plsql.activerecord_class = TestModel
     expect(plsql.schema_name).to eq('HR')
   end
+
+  it "should safely close cursors in threaded environment" do
+    expect {
+      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, t1].each { |t| t.join }
+    }.not_to raise_error
+  end
+
 end if defined?(ActiveRecord)
 
 describe "DBMS_OUTPUT logging" do