diff --git a/src/Makefile.am b/src/Makefile.am
index cbe656bb81bee16fc171081e463a0399676f97e9..69ba4ade2e3fd64b07bbea7ca267cf00d6242ade 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -23,7 +23,7 @@ run-one-body-sample-gdb: one-body-sample
 	libtool --mode execute gdb ./one-body-sample
 
 one_body_sample_SOURCES = \
-	one-body-sample.cc
+	one-body-sample.cc LambertW.cc
 one_body_sample_CPPFLAGS = \
 	$(AM_CPPFLAGS) -Dsrcdir=\"$(srcdir)\"
 
diff --git a/src/one-body-sample.cc b/src/one-body-sample.cc
index 38e50f7885be8ce7851bc0aee077991ff7aa44b0..db42af2df4b4afe693c56663c541e81eed96a2b8 100644
--- a/src/one-body-sample.cc
+++ b/src/one-body-sample.cc
@@ -15,6 +15,8 @@
 
 #include "boost/format.hpp"
 
+#include "LambertW.h"
+
 #include <dune/common/bitsetvector.hh>
 #include <dune/common/exceptions.hh>
 #include <dune/common/fmatrix.hh>