diff --git a/CMakeLists.txt b/CMakeLists.txt
index 61e2e8ec3955921ad71d0b15c97f68a27b85e8f4..7630db398c8271847e1388553f6a2c5b716c42f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,9 +31,9 @@ include_directories("${CMAKE_CURRENT_SOURCE_DIR}/boost_teqp")
 #set(EIGEN_BUILD_DOC FALSE CACHE BOOL "Turn off Eigen snippets in their docs")
 #set(EIGEN_TEST_NOQT TRUE CACHE BOOL "Turn off Eigen tests of Qt")
 #set(BUILD_TESTING FALSE CACHE BOOL "Turn off Eigen tests")
-#set(Eigen3_DIR "${CMAKE_CURRENT_SOURCE_DIR}/externals/Eigen" CACHE INTERNAL "Path to Eigen, for autodiff")
 # add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/externals/Eigen")
 
+set(Eigen3_DIR "${CMAKE_CURRENT_SOURCE_DIR}/externals/Eigen" CACHE INTERNAL "Path to Eigen, for autodiff")
 set(AUTODIFF_BUILD_TESTS FALSE CACHE BOOL "No autodiff tests")
 set(AUTODIFF_BUILD_PYTHON FALSE CACHE BOOL "No autodiff python")
 set(AUTODIFF_BUILD_EXAMPLES FALSE CACHE BOOL "No autodiff examples")