diff --git a/ql/src/codeql_ql/ast/internal/Builtins.qll b/ql/src/codeql_ql/ast/internal/Builtins.qll
index 1f9638ed63c..d276acba5df 100644
--- a/ql/src/codeql_ql/ast/internal/Builtins.qll
+++ b/ql/src/codeql_ql/ast/internal/Builtins.qll
@@ -42,7 +42,7 @@ predicate isBuiltinMember(string sig) {
       "string string.toLowerCase()", "string string.toUpperCase()", "string string.trim()",
       "int date.daysTo(date)", "int date.getDay()", "int date.getHours()", "int date.getMinutes()",
       "int date.getMonth()", "int date.getSeconds()", "int date.getYear()",
-      "string date.toString()", "string date.toISO()"
+      "string date.toString()", "string date.toISO()", "string int.toUnicode()"
     ]
 }