diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2df11da..cc51cb9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,6 +37,7 @@ else()
         "Matrix.cpp"
         "Axis.cpp"
         "AngleAxis.cpp"
+        "Direction.cpp"
     )
 
     enable_testing()