diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index 7ced7c3279..71e2057b2b 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -172,7 +172,9 @@ if(USE_MMAP OR USE_VOXELS)
     else()
         set(BOOST_COMPONENTS ${BOOST_COMPONENTS} iostreams)
     endif()
-    add_definitions(-DUSE_MMAP)
+	if(USE_MMAP)
+		add_definitions(-DUSE_MMAP)
+	endif()
 endif()
 
 if (IFCXML_SUPPORT)