diff --git a/configure.ac b/configure.ac
index 77f20d85..83c104c3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -176,7 +176,8 @@ if test "x$found_ncurses" = xno; then
 	)
 fi
 if test "x$found_ncurses" = xyes; then
-	CPPFLAGS="$LIBNCURSES_CFLAGS $LIBTINFO_CFLAGS $CPPFLAGS"
+	AM_CFLAGS="$LIBNCURSES_CFLAGS $LIBTINFO_CFLAGS $AM_CFLAGS"
+	CFLAGS="$LIBNCURSES_CFLAGS $LIBTINFO_CFLAGS $CFLAGS"
 	LIBS="$LIBNCURSES_LIBS $LIBTINFO_LIBS $LIBS"
 else
 	# pkg-config didn't work, try ncurses.