diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3441178..19fa5dd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,11 @@
 
+# define build type
+IF( DEFINED CMAKE_BUILD_TYPE )
+  SET( CMAKE_BUILD_TYPE ${CMAKE_BUILD_TYPE} CACHE STRING "Set to either \"Release\" or \"Debug\"" )
+ELSE()
+  SET( CMAKE_BUILD_TYPE Release CACHE STRING "Set to either \"Release\" or \"Debug\"" )
+ENDIF()
+
 PROJECT(openEMS CXX)
 cmake_minimum_required(VERSION 2.8)