diff --git a/bench/benchFFT.cpp b/bench/benchFFT.cpp
index 14f5063fb..4b6cabb55 100644
--- a/bench/benchFFT.cpp
+++ b/bench/benchFFT.cpp
@@ -26,6 +26,10 @@
 #include <vector>
 #include <Eigen/Core>
 #include <bench/BenchTimer.h>
+#ifdef USE_FFTW
+#include <fftw3.h>
+#endif
+
 #include <unsupported/Eigen/FFT>
 
 using namespace Eigen;
diff --git a/unsupported/Eigen/FFT b/unsupported/Eigen/FFT
index 03f8504a4..dc7e85908 100644
--- a/unsupported/Eigen/FFT
+++ b/unsupported/Eigen/FFT
@@ -32,7 +32,8 @@
 // FFTW: faster, GPL -- incompatible with Eigen in LGPL form, bigger code size
 #ifdef FFTW_ESTIMATE  // definition of FFTW_ESTIMATE indicates the caller has included fftw3.h, we can use FFTW routines
 #include "src/FFT/ei_fftw_impl.h"
-// #define DEFAULT_FFT_IMPL ei_fftw_impl
+#undef DEFAULT_FFT_IMPL
+#define DEFAULT_FFT_IMPL ei_fftw_impl
 #endif
 
 // intel Math Kernel Library: fastest, commerical -- incompatible with Eigen in GPL form
diff --git a/unsupported/test/FFT.cpp b/unsupported/test/FFT.cpp
index 32d1393d0..28230e1c4 100644
--- a/unsupported/test/FFT.cpp
+++ b/unsupported/test/FFT.cpp
@@ -23,6 +23,11 @@
 // Eigen. If not, see <http://www.gnu.org/licenses/>.
 
 #include "main.h"
+//#define USE_FFTW
+#ifdef USE_FFTW
+#include <fftw3.h>
+#endif
+
 #include <unsupported/Eigen/FFT>
 
 using namespace std;