diff --git a/src/DeviceManager.h b/src/DeviceManager.h
index b6d1a8439..82ba0824d 100644
--- a/src/DeviceManager.h
+++ b/src/DeviceManager.h
@@ -18,6 +18,8 @@
 #ifndef __AUDACITY_DEVICEMANAGER__
 #define __AUDACITY_DEVICEMANAGER__
 
+#include "Experimental.h"
+
 #include <vector>
 #include "wx/wx.h"
 
diff --git a/src/RealFFTf.h b/src/RealFFTf.h
index 6e7b44383..497af02b6 100644
--- a/src/RealFFTf.h
+++ b/src/RealFFTf.h
@@ -1,6 +1,8 @@
 #ifndef __realfftf_h
 #define __realfftf_h
 
+#include "Experimental.h"
+
 #define fft_type float
 struct FFTParam {
    int *BitReversed;
diff --git a/src/effects/NoiseRemoval.h b/src/effects/NoiseRemoval.h
index 193265477..2f55fc1b9 100644
--- a/src/effects/NoiseRemoval.h
+++ b/src/effects/NoiseRemoval.h
@@ -14,6 +14,8 @@
 
 #include "../Audacity.h"
 
+#include "../Experimental.h"
+
 #if !defined(EXPERIMENTAL_NOISE_REDUCTION)
 
 #include "Effect.h"
diff --git a/src/prefs/KeyConfigPrefs.h b/src/prefs/KeyConfigPrefs.h
index 07bbd0b1d..effc2d6a8 100644
--- a/src/prefs/KeyConfigPrefs.h
+++ b/src/prefs/KeyConfigPrefs.h
@@ -12,6 +12,8 @@
 #ifndef __AUDACITY_KEY_CONFIG_PREFS__
 #define __AUDACITY_KEY_CONFIG_PREFS__
 
+#include "../Experimental.h"
+
 class ShuttleGui;
 
 #if defined(EXPERIMENTAL_KEY_VIEW)
diff --git a/src/toolbars/TranscriptionToolBar.h b/src/toolbars/TranscriptionToolBar.h
index 8ae652694..c2e3cc119 100644
--- a/src/toolbars/TranscriptionToolBar.h
+++ b/src/toolbars/TranscriptionToolBar.h
@@ -14,6 +14,7 @@
 #define __AUDACITY_TRANSCRIPTION_TOOLBAR__
 
 #include "ToolBar.h"
+#include "../Experimental.h"
 
 #include <wx/brush.h>
 #include <wx/pen.h>
diff --git a/src/widgets/ASlider.h b/src/widgets/ASlider.h
index 7d22aba55..7544fd4c1 100644
--- a/src/widgets/ASlider.h
+++ b/src/widgets/ASlider.h
@@ -13,6 +13,8 @@
 #ifndef __AUDACITY_SLIDER__
 #define __AUDACITY_SLIDER__
 
+#include "../Experimental.h"
+
 #include <wx/defs.h>
 #include <wx/window.h>
 #include <wx/dialog.h>