diff -Naur harfbuzz-2.8.1/src/hb-buffer.hh harfbuzz-2.8.1.serenity/src/hb-buffer.hh
--- harfbuzz-2.8.1/src/hb-buffer.hh	2021-05-04 02:09:38.000000000 +0200
+++ harfbuzz-2.8.1.serenity/src/hb-buffer.hh	2021-05-08 05:22:34.579810445 +0200
@@ -166,7 +166,7 @@
 #ifndef HB_NDEBUG
     unsigned int end = start + count;
     assert (end <= 8);
-    unsigned int bits = (1u<<end) - (1u<<start);
+    [[maybe_unused]] unsigned int bits = (1u<<end) - (1u<<start);
     assert (bits == (allocated_var_bits & bits));
 #endif
   }