--- waterfox-6.6.4/intl/lwbrk/LineBreaker.cpp
+++ waterfox-6.6.4/intl/lwbrk/LineBreaker.cpp
@@ -448,16 +448,17 @@
       /* E_BASE = 40,                       [EB] */ CLASS_BREAKABLE,
       /* E_MODIFIER = 41,                   [EM] */ CLASS_CHARACTER,
       /* ZWJ = 42,                          [ZWJ]*/ CLASS_CHARACTER,
       /* AKSARA = 43,                       [AK] */ CLASS_CHARACTER,
       /* AKSARA_PREBASE = 44,               [AP] */ CLASS_CHARACTER,
       /* AKSARA_START = 45,                 [AS] */ CLASS_CHARACTER,
       /* VIRAMA_FINAL = 46,                 [VF] */ CLASS_CHARACTER,
       /* VIRAMA = 47,                       [VI] */ CLASS_CHARACTER,
+      /* UNAMBIGUOUS_HYPHEN = 48,           [HH] */ CLASS_CHARACTER,
   };
 
   static_assert(U_LB_COUNT == std::size(sUnicodeLineBreakToClass),
                 "Gecko vs ICU LineBreak class mismatch");
 
   auto cls = GetLineBreakClass(u);
   MOZ_ASSERT(cls < std::size(sUnicodeLineBreakToClass));