diff --git a/icu4c/source/i18n/unicode/rbt.h b/icu4c/source/i18n/unicode/rbt.h
index 91ed0708a2..50036abc1d 100644
--- a/icu4c/source/i18n/unicode/rbt.h
+++ b/icu4c/source/i18n/unicode/rbt.h
@@ -455,6 +455,7 @@ public:
         MISMATCHED_SEGMENT_DELIMITERS,
         MISPLACED_ANCHOR_START,
         MISPLACED_CURSOR_OFFSET,
+        MISPLACED_QUANTIFIER,
         MISSING_OPERATOR,
         MISSING_SEGMENT_CLOSE,
         MULTIPLE_ANTE_CONTEXTS,
@@ -464,7 +465,7 @@ public:
         UNDEFINED_SEGMENT_REFERENCE,
         UNDEFINED_VARIABLE,
         UNQUOTED_SPECIAL,
-        UNTERMINATED_QUOTE
+        UNTERMINATED_QUOTE,
     };
 
 private: