Index: cmake/Modules/MacroEnsureOutOfSourceBuild.cmake
===================================================================
--- cmake/Modules/MacroEnsureOutOfSourceBuild.cmake
+++ cmake/Modules/MacroEnsureOutOfSourceBuild.cmake
@@ -2,7 +2,7 @@
 
 macro( MACRO_ENSURE_OUT_OF_SOURCE_BUILD _errorMessage )
 
-string( COMPARE EQUAL "${CMAKE_SOURCE_DIR}" "${CMAKE_BINARY_DIR}" _insource )
+string( COMPARE EQUAL "${CMAKE_CURRENT_SOURCE_DIR}" "${CMAKE_BINARY_DIR}" _insource )
 if( _insource )
  message( SEND_ERROR "${_errorMessage}" )
  message( FATAL_ERROR