diff --git a/DEPENDENCIES b/DEPENDENCIES
index dc15ee20d..28e6a0301 100644
--- a/DEPENDENCIES
+++ b/DEPENDENCIES
@@ -1,3 +1,3 @@
 vendorpull https://github.com/sourcemeta/vendorpull 1dcbac42809cf87cb5b045106b863e17ad84ba02
-core https://github.com/sourcemeta/core 87a66bfc8f243640beb34998f35ff1dea5e77095
+core https://github.com/sourcemeta/core ac96b5fba550a5097d174c1681ba3155cb3e3914
 jsonschema-test-suite https://github.com/json-schema-org/JSON-Schema-Test-Suite a247442bca7a4798ab6187e035200feacd5423ed
diff --git a/vendor/core/src/core/regex/preprocess.h b/vendor/core/src/core/regex/preprocess.h
index 227b41c40..b844aa2cf 100644
--- a/vendor/core/src/core/regex/preprocess.h
+++ b/vendor/core/src/core/regex/preprocess.h
@@ -618,12 +618,21 @@ inline auto preprocess_regex(const std::string &pattern)
       const bool starts_with_nested =
           !nested_content.empty() && nested_content[0] == '[';
 
+      // Check if the character after the simple bracket end continues
+      // the class with more v-flag syntax (another nested class or outer
+      // closing bracket). This distinguishes true v-flag nesting like
+      // [[a-z][A-Z]] from a literal [ inside a standard class like [[(]
+      const bool after_simple_continues_class =
+          simple_end < pattern.size() &&
+          (pattern[simple_end] == '[' || pattern[simple_end] == ']');
+
       // Use v-flag mode if:
       // 1. Nested content has v-flag operators (-- or &&), OR
       // 2. Content starts with [ (indicating v-flag nested class syntax)
-      //    AND the ends differ (so there's actual nesting being tracked)
+      //    AND the ends differ AND the class continues after simple end
       const bool use_v_flag =
-          nested_has_ops || (starts_with_nested && simple_end != nested_end);
+          nested_has_ops || (starts_with_nested && simple_end != nested_end &&
+                             after_simple_continues_class);
 
       if (use_v_flag) {
         const auto expanded = expand_char_class(nested_content);