diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1dc794f..acac809 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,11 +1,25 @@
 
 # CMAKE_INSTALL_PREFIX defaults to /usr/local.
 
-cmake_minimum_required(VERSION 2.6)
+cmake_minimum_required(VERSION 3.1)
 project("mpw-shell")
 set (PROJECT_TYPE "CXX")
 set (PROJECT_NAME "MPW Shell")
 
+#
+# build config.h
+#
+
+INCLUDE (CheckFunctionExists)
+SET(CMAKE_EXTRA_INCLUDE_FILES stdio.h)
+CHECK_FUNCTION_EXISTS(dprintf HAVE_DPRINTF)
+SET(CMAKE_EXTRA_INCLUDE_FILES)
+
+CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/config.h.in ${CMAKE_CURRENT_BINARY_DIR}/config.h)
+
+
+
+
 set(CMAKE_CXX_FLAGS "-g -Wall -Wno-unused-variable -Wno-multichar -O1")
 
 if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
diff --git a/config.h.in b/config.h.in
new file mode 100644
index 0000000..b91b2fc
--- /dev/null
+++ b/config.h.in
@@ -0,0 +1,7 @@
+#ifndef __mpw_shell_config_h__
+#define __mpw_shell_config_h__
+
+#cmakedefine HAVE_DPRINTF
+
+#endif
+