--- a/projectbuilders/CMakeLists.txt	2015-02-02 15:19:46.000000000 +0100
+++ b/projectbuilders/CMakeLists.txt	2015-07-06 22:51:22.083293634 +0200
@@ -1,5 +1,5 @@
 
 add_subdirectory(makebuilder)
-add_subdirectory(ninjabuilder)
+ecm_optional_add_subdirectory(ninjabuilder)
 ecm_optional_add_subdirectory(cmakebuilder)