diff --git a/src/hb-unicode-private.hh b/src/hb-unicode-private.hh
index eaf151a52ac456c0bcddc229564b89b355c044e3..c781035aa9a7a814daef54f486305d4dfc4b0b29 100644
--- a/src/hb-unicode-private.hh
+++ b/src/hb-unicode-private.hh
@@ -99,6 +99,7 @@ extern HB_INTERNAL const hb_unicode_funcs_t _hb_icu_unicode_funcs;
 #define _hb_unicode_funcs_default _hb_icu_unicode_funcs
 #else
 #define HB_UNICODE_FUNCS_NIL 1
+extern HB_INTERNAL const hb_unicode_funcs_t _hb_unicode_funcs_nil;
 #define _hb_unicode_funcs_default _hb_unicode_funcs_nil
 #endif