diff --git a/configure.ac b/configure.ac
index 2ae9e67900..0a2ab68dd2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -407,9 +407,7 @@ AC_SUBST(CLIENTLIBS)
 CLIENTGUIFLAGS="-DNOCLIPBOARD -DNOTASKBAR"
 
 if test "${enable_debug}" = yes; then
-    echo "DEBUG: before mangling CLIENTGUIFLAGS='$CLIENTGUIFLAGS'"
-    CLIENTGUIFLAGS="${CLIENTGUIFLAGS} -D__WXDEBUG__"
-    echo "DEBUG: after mangling CLIENTGUIFLAGS='$CLIENTGUIFLAGS'"
+    CLIENTGUIFLAGS="${CLIENTGUIFLAGS} -D__WXDEBUG__ -D_DEBUG -DDEBUG"
 fi
 
 CLIENTGUILIBS=${WX_LIBS}