diff --git a/build/cmake/setup.h.in b/build/cmake/setup.h.in
index 79b36148a7..c94d05989a 100644
--- a/build/cmake/setup.h.in
+++ b/build/cmake/setup.h.in
@@ -148,11 +148,6 @@
 
 
 
-#ifndef wxUSE_UNICODE
-    #cmakedefine01 wxUSE_UNICODE
-#endif
-
-
 #cmakedefine01 wxUSE_EXCEPTIONS
 
 #cmakedefine01 wxUSE_EXTENDED_RTTI
diff --git a/include/wx/android/setup.h b/include/wx/android/setup.h
index 04eb147ddc..8e3d287524 100644
--- a/include/wx/android/setup.h
+++ b/include/wx/android/setup.h
@@ -180,18 +180,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/include/wx/gtk/setup.h b/include/wx/gtk/setup.h
index 0dd052d801..366abd5a3f 100644
--- a/include/wx/gtk/setup.h
+++ b/include/wx/gtk/setup.h
@@ -181,18 +181,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/include/wx/msw/setup.h b/include/wx/msw/setup.h
index a1905621cd..90f356c513 100644
--- a/include/wx/msw/setup.h
+++ b/include/wx/msw/setup.h
@@ -181,18 +181,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/include/wx/osx/setup.h b/include/wx/osx/setup.h
index d2cc1f0d8a..149ffee681 100644
--- a/include/wx/osx/setup.h
+++ b/include/wx/osx/setup.h
@@ -187,18 +187,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/include/wx/platform.h b/include/wx/platform.h
index 66e1ab2421..28a3f66641 100644
--- a/include/wx/platform.h
+++ b/include/wx/platform.h
@@ -197,30 +197,26 @@
 
 
 /*
-   adjust the Unicode setting: wxUSE_UNICODE should be defined as 0 or 1
-   and is used by wxWidgets, _UNICODE and/or UNICODE may be defined or used by
-   the system headers so bring these settings in sync
+   Always define wxUSE_UNICODE as 1 for compatibility.
+
+   Additionally, define _UNICODE and UNICODE too: this is used by MSW SDK/CRT
+   headers and also may be used by wx applications code.
  */
 
-/* set wxUSE_UNICODE to 1 if UNICODE or _UNICODE is defined */
-#if defined(_UNICODE) || defined(UNICODE)
-#   undef wxUSE_UNICODE
+#ifdef wxUSE_UNICODE
+#   if wxUSE_UNICODE != 1
+#       error "wxUSE_UNICODE may be only defined as 1"
+#   endif
+#else
 #   define wxUSE_UNICODE 1
-#else /* !UNICODE */
-#   ifndef wxUSE_UNICODE
-#       define wxUSE_UNICODE 0
-#   endif
-#endif /* UNICODE/!UNICODE */
+#endif
 
-/* and vice versa: define UNICODE and _UNICODE if wxUSE_UNICODE is 1 */
-#if wxUSE_UNICODE
-#   ifndef _UNICODE
-#       define _UNICODE
-#   endif
-#   ifndef UNICODE
-#       define UNICODE
-#   endif
-#endif /* wxUSE_UNICODE */
+#ifndef _UNICODE
+#    define _UNICODE
+#endif
+#ifndef UNICODE
+#    define UNICODE
+#endif
 
 
 
diff --git a/include/wx/setup_inc.h b/include/wx/setup_inc.h
index f76e744321..d2f534ee96 100644
--- a/include/wx/setup_inc.h
+++ b/include/wx/setup_inc.h
@@ -177,18 +177,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/include/wx/univ/setup.h b/include/wx/univ/setup.h
index fcda796cec..3ed6cd3113 100644
--- a/include/wx/univ/setup.h
+++ b/include/wx/univ/setup.h
@@ -180,18 +180,6 @@
 #define wxUSE_DEBUG_NEW_ALWAYS 0
 
 
-// ----------------------------------------------------------------------------
-// Unicode support
-// ----------------------------------------------------------------------------
-
-// This option is deprecated: the library should be always built in Unicode mode
-// now, only set wxUSE_UNICODE to 0 to compile legacy code in ANSI mode if
-// absolutely necessary -- updating it is strongly recommended as the ANSI mode
-// will disappear completely in future wxWidgets releases.
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 1
-#endif
-
 // ----------------------------------------------------------------------------
 // global features
 // ----------------------------------------------------------------------------
diff --git a/setup.h.in b/setup.h.in
index 384e818e4e..ace1560807 100644
--- a/setup.h.in
+++ b/setup.h.in
@@ -151,11 +151,6 @@
 
 
 
-#ifndef wxUSE_UNICODE
-    #define wxUSE_UNICODE 0
-#endif
-
-
 #define wxUSE_EXCEPTIONS    0
 
 #define wxUSE_EXTENDED_RTTI 0