diff --git a/src/hb-ot-font.cc b/src/hb-ot-font.cc
index fa5e30c9c..c89a1954a 100644
--- a/src/hb-ot-font.cc
+++ b/src/hb-ot-font.cc
@@ -64,7 +64,9 @@
 using hb_ot_font_cmap_cache_t    = hb_cache_t<21, 16, 8, true>;
 using hb_ot_font_advance_cache_t = hb_cache_t<24, 16, 8, true>;
 
+#ifndef HB_NO_OT_FONT_CMAP_CACHE
 static hb_user_data_key_t hb_ot_font_cmap_cache_user_data_key;
+#endif
 
 struct hb_ot_font_t
 {