diff --git a/CMakeLists.txt b/CMakeLists.txt
index 79b4157..3be03fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,6 +29,20 @@ option(Boost_USE_STATIC_LIBS "Use Boost static libraries" OFF)
 option(PHAETHON_BUILD_DOCUMENTATION "Use Doxygen to create the HTML based API documentation" OFF)
 
 
+# -------------------------------------------------------------------------
+# default build type
+
+set(default_build_type "Debug")
+if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+  message(STATUS "Setting build type to '${default_build_type}' as none was specified.")
+  set(CMAKE_BUILD_TYPE "${default_build_type}" CACHE
+      STRING "Choose the type of build." FORCE)
+  # Set the possible values of build type for cmake-gui
+  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
+    "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
+endif()
+
+
 # -------------------------------------------------------------------------
 # load some cmake modules from cmake/ subfolder
 list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)