diff --git a/tests/allheaders.cpp b/tests/allheaders.cpp
index 34629bd524..575d38fbfb 100644
--- a/tests/allheaders.cpp
+++ b/tests/allheaders.cpp
@@ -423,7 +423,10 @@
     GCC_TURN_OFF(padded)
 #endif // gcc >= 4.6
 
-#if !wxUSE_UTF8_LOCALE_ONLY
+// ANSI build hasn't been updated to work without implicit wxString encoding
+// and never will be, as it will be removed soon anyhow. And in UTF-8-only
+// build we actually want to use implicit encoding (UTF-8).
+#if wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
 #define wxNO_IMPLICIT_WXSTRING_ENCODING
 #endif