diff --git a/cpp/Makefile.am b/cpp/Makefile.am
index dbdd08a89..982bdb525 100644
--- a/cpp/Makefile.am
+++ b/cpp/Makefile.am
@@ -49,7 +49,8 @@ testMatrix_LDADD   = libgtsam.la
 
 # GTSAM basics
 # The header files will be installed in ~/include/gtsam
-headers = gtsam.h Value.h Testable.h Factor.h Conditional.h Ordering.h Ordering-inl.h
+headers = gtsam.h Value.h Testable.h Factor.h Conditional.h 
+headers += Ordering.h Ordering-inl.h numericalDerivative.h
 sources += Ordering.cpp  
 example = smallExample.cpp