diff --git a/src/AudacityApp.h b/src/AudacityApp.h
index daa3d509b..c60f737a5 100644
--- a/src/AudacityApp.h
+++ b/src/AudacityApp.h
@@ -24,7 +24,6 @@
 #include <wx/dir.h>
 #include <wx/docview.h>
 #include <wx/snglinst.h>
-#include <wx/socket.h>
 #include <wx/timer.h>
 
 #include "widgets/FileHistory.h"
@@ -34,6 +33,9 @@
 #include <wx/debugrpt.h>
 #endif
 
+class wxSocketEvent;
+class wxSocketServer;
+
 class IPCServ;
 class Importer;
 class CommandHandler;
diff --git a/src/ShuttleGui.h b/src/ShuttleGui.h
index ab37cbe88..969020c0f 100644
--- a/src/ShuttleGui.h
+++ b/src/ShuttleGui.h
@@ -57,7 +57,6 @@ class wxStaticText;
 class wxTreeCtrl;
 class wxTextCtrl;
 class wxSlider;
-class wxTreeListCtrl;
 class wxNotebook;
 typedef wxWindow wxNotebookPage;  // so far, any window can be a page
 class wxButton;
diff --git a/src/effects/nyquist/Nyquist.h b/src/effects/nyquist/Nyquist.h
index 91c30eeaf..45b2d06f7 100644
--- a/src/effects/nyquist/Nyquist.h
+++ b/src/effects/nyquist/Nyquist.h
@@ -12,7 +12,6 @@
 #define __AUDACITY_EFFECT_NYQUIST__
 
 #include <wx/datetime.h>
-#include <wx/textbuf.h>
 
 #include "../Effect.h"
 
diff --git a/src/prefs/KeyConfigPrefs.h b/src/prefs/KeyConfigPrefs.h
index a24fead73..3ba6bdb3d 100644
--- a/src/prefs/KeyConfigPrefs.h
+++ b/src/prefs/KeyConfigPrefs.h
@@ -16,7 +16,6 @@ class CommandManager;
 class ShuttleGui;
 
 #include <wx/defs.h>
-#include <wx/srchctrl.h>
 #include <wx/timer.h>
 
 #include "../widgets/KeyView.h"
diff --git a/src/prefs/PrefsDialog.h b/src/prefs/PrefsDialog.h
index db7559fab..ddb09471e 100644
--- a/src/prefs/PrefsDialog.h
+++ b/src/prefs/PrefsDialog.h
@@ -13,10 +13,11 @@
 #define __AUDACITY_PREFS_DIALOG__
 
 #include <vector>
-#include <wx/treebook.h>
 #include "../widgets/wxPanelWrapper.h"
 #include "../Internat.h"
 
+class wxTreebook;
+class wxTreeEvent;
 class PrefsPanel;
 class PrefsPanelFactory;
 class ShuttleGui;