Fix C++ build.

diff --git a/dsp/tempotracking/DownBeat.cpp b/dsp/tempotracking/DownBeat.cpp
index 8de1b64..12dd066 100644
--- a/dsp/tempotracking/DownBeat.cpp
+++ b/dsp/tempotracking/DownBeat.cpp
@@ -13,6 +13,8 @@
     COPYING included with this distribution for more information.
 */
 
+#include <cstdlib>
+
 #include "DownBeat.h"
 
 #include "maths/MathAliases.h"
@@ -21,7 +23,6 @@
 #include "dsp/transforms/FFT.h"
 
 #include <iostream>
-#include <cstdlib>
 
 DownBeat::DownBeat(float originalSampleRate,
                    size_t decimationFactor,
diff --git a/dsp/tempotracking/TempoTrackV2.cpp b/dsp/tempotracking/TempoTrackV2.cpp
index 4834a85..f5d73be 100644
--- a/dsp/tempotracking/TempoTrackV2.cpp
+++ b/dsp/tempotracking/TempoTrackV2.cpp
@@ -13,10 +13,11 @@
     COPYING included with this distribution for more information.
 */
 
+#include <cstdlib>
+
 #include "TempoTrackV2.h"
 
 #include <cmath>
-#include <cstdlib>
 #include <iostream>
 
 #include "maths/MathUtilities.h"