diff --git a/CMakeLists.txt b/CMakeLists.txt
index 16f75fca9..4015f2813 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,7 +22,7 @@
 set(CMAKE_LEGACY_CYGWIN_WIN32 0)
 
 project(FLTK)
-cmake_minimum_required(VERSION 2.6)
+cmake_minimum_required(VERSION 2.6.3)
 
 #######################################################################
 # define some macros