diff --git a/src/hf_tokenizer.cpp b/src/hf_tokenizer.cpp
index 6d7e742..03d7816 100644
--- a/src/hf_tokenizer.cpp
+++ b/src/hf_tokenizer.cpp
@@ -56,7 +56,7 @@ Error HFTokenizer::load(const std::string& path) {
   json parsed_json;
   try {
     parsed_json = json::parse(contents);
-  } catch (const json::exception& e) {
+  } catch (const std::exception& e) {
     TK_LOG(Error, "Error parsing json file: %s", e.what());
     return Error::LoadFailure;
   }
@@ -76,7 +76,7 @@ Error HFTokenizer::load(const std::string& path) {
 
     // Store for future use.
     special_token_map_.emplace(std::move(special_token_map));
-  } catch (const json::out_of_range& e) {
+  } catch (const std::exception& e) {
     TK_LOG(Info, "Could not parse special tokens: %s", e.what());
     return Error::LoadFailure;
   }
@@ -96,7 +96,7 @@ Error HFTokenizer::load(const std::string& path) {
 
     auto token_map = TK_UNWRAP(detail::build_token_map(std::move(token_pairs)));
     token_map_.emplace(std::move(token_map));
-  } catch (const json::out_of_range& e) {
+  } catch (const std::exception& e) {
     TK_LOG(Info, "Could not parse tokens: %s", e.what());
     return Error::LoadFailure;
   }
@@ -114,7 +114,7 @@ Error HFTokenizer::load(const std::string& path) {
     } else {
       TK_LOG(Info, "Normalizer field is null, skipping");
     }
-  } catch (const json::out_of_range& e) {
+  } catch (const std::exception& e) {
     // No "Normalizer" field found
     TK_LOG(
         Info,
@@ -129,7 +129,7 @@ Error HFTokenizer::load(const std::string& path) {
                         .parse_json(parsed_json.at("pre_tokenizer"))
                         .create();
     TK_LOG(Info, "Pretokenizer set up");
-  } catch (const json::out_of_range& e) {
+  } catch (const std::exception& e) {
     TK_LOG(Info, "Could not parse pre_tokenizer: %s", e.what());
     return Error::LoadFailure;
   }
@@ -138,7 +138,7 @@ Error HFTokenizer::load(const std::string& path) {
   try {
     _decoder =
         TokenDecoderConfig().parse_json(parsed_json.at("decoder")).create();
-  } catch (const json::out_of_range&) {
+  } catch (const std::exception&) {
     // No decoder specified
   }
 
@@ -192,7 +192,7 @@ Error HFTokenizer::load(const std::string& path) {
         "Built merge ranks map with %" PRId64 " entries",
         static_cast<int64_t>(merge_ranks.size()));
     merge_ranks_.emplace(std::move(merge_ranks));
-  } catch (const json::out_of_range& e) {
+  } catch (const std::exception& e) {
     TK_LOG(Error, "Could not parse merges: %s", e.what());
     return Error::LoadFailure;
   }
@@ -211,7 +211,7 @@ Error HFTokenizer::load(const std::string& path) {
     json parsed_config_json;
     try {
       parsed_config_json = json::parse(config_contents);
-    } catch (const json::exception& e) {
+    } catch (const std::exception& e) {
       TK_LOG(Error, "Error parsing model config json json file: %s", e.what());
       return Error::LoadFailure;
     }
@@ -239,7 +239,7 @@ Error HFTokenizer::load(const std::string& path) {
       }
       bos_tok_ = *bos_res;
       eos_tok_ = *eos_res;
-    } catch (const json::out_of_range& e) {
+    } catch (const std::exception& e) {
       TK_LOG(Error, "Could not eos/bos from tokenizer config: %s", e.what());
       return Error::LoadFailure;
     }
diff --git a/src/pre_tokenizer.cpp b/src/pre_tokenizer.cpp
index 279fc39..42f0f97 100644
--- a/src/pre_tokenizer.cpp
+++ b/src/pre_tokenizer.cpp
@@ -48,14 +48,15 @@ PreTokenizer::Ptr PreTokenizerConfig::create() const {
     }
 
     // Validate invert parameter
-    bool invert_flag = invert ? *invert : false;
-    if (invert_flag) {
+    const bool invert_flag = invert ? *invert : false;
+    const bool delimiter_flag = is_delimiter ? *is_delimiter : false;
+    if (invert_flag && delimiter_flag) {
       throw std::runtime_error(
-          "invert=true is not supported for Split PreTokenizer. Only invert=false is supported.");
+          "invert=true is not supported for Split PreTokenizer with a String pattern.");
     }
 
-    return PreTokenizer::Ptr(new RegexPreTokenizer(
-        *pattern, is_delimiter ? *is_delimiter : false, behavior_str));
+    return PreTokenizer::Ptr(
+        new RegexPreTokenizer(*pattern, delimiter_flag, behavior_str));
   }
   if (type == "Digits") {
     if (individual_digits) {
@@ -143,16 +144,51 @@ PreTokenizerConfig& PreTokenizerConfig::parse_json(const json& json_config) {
 
 // RegexPreTokenizer ///////////////////////////////////////////////////////////
 
+namespace {
+
+// Make Hugging Face Split patterns RE2-compatible by:
+// 1) removing the negative look-ahead "\s+(?!\S)" (→ "\s+$")
+// 2) expanding the inline case-insensitive contractions
+//    "(?i:'s|'t|'re|'ve|'m|'ll|'d)" into explicit alternations.
+static void replace_all_in_place(
+    std::string& input,
+    const std::string& needle,
+    const std::string& replacement) {
+  if (needle.empty()) {
+    return;
+  }
+  size_t search_pos = 0;
+  while ((search_pos = input.find(needle, search_pos)) != std::string::npos) {
+    input.replace(search_pos, needle.size(), replacement);
+    search_pos += replacement.size();
+  }
+}
+
+static std::string make_re2_compatible(std::string pattern) {
+  const std::string lookahead_trailing_space = R"(\s+(?!\S))";
+  const std::string trailing_space_replacement = R"(\s+$)";
+  replace_all_in_place(
+      pattern, lookahead_trailing_space, trailing_space_replacement);
+  const std::string ci_contractions = R"((?i:'s|'t|'re|'ve|'m|'ll|'d))";
+  const std::string contractions_expanded =
+      "(?:'s|'S|'t|'T|'re|'RE|'ve|'VE|'m|'M|'ll|'LL|'d|'D)";
+  replace_all_in_place(pattern, ci_contractions, contractions_expanded);
+  return pattern;
+}
+
+} // namespace
+
 std::unique_ptr<IRegex> RegexPreTokenizer::create_regex_(
     const std::string& pattern) {
   assert(!pattern.empty());
-  return TK_UNWRAP_THROW(create_regex(pattern));
+  return TK_UNWRAP_THROW(create_regex(make_re2_compatible(pattern)));
 }
 
 std::vector<std::string> RegexPreTokenizer::pre_tokenize(
     const std::string& input) const {
-  if (!regex_)
+  if (!regex_) {
     return {};
+  }
 
   std::vector<std::string> results;
   auto matches = regex_->find_all(input);
diff --git a/test/test_hf_tokenizer.py b/test/test_hf_tokenizer.py
index 6162dc1..dbed244 100644
--- a/test/test_hf_tokenizer.py
+++ b/test/test_hf_tokenizer.py
@@ -48,3 +48,16 @@ def test_llama3_2_1b(self) -> None:
         tokens = tokenizer.encode(PROMPT)
         cpp_tokens = cpp_tokenizer.encode(PROMPT, bos=1)
         self.assertEqual(tokens, cpp_tokens)
+
+    def test_phi_4_mini(self) -> None:
+        tokenizer = AutoTokenizer.from_pretrained(
+            "software-mansion/react-native-executorch-phi-4-mini"
+        )
+        tokenizer_path = tokenizer.save_pretrained(self.temp_dir.name)[-1]
+
+        cpp_tokenizer = CppHFTokenizer()
+        cpp_tokenizer.load(tokenizer_path)
+
+        tokens = tokenizer.encode(PROMPT)
+        cpp_tokens = cpp_tokenizer.encode(PROMPT)
+        self.assertEqual(tokens, cpp_tokens)
diff --git a/third-party/targets.bzl b/third-party/targets.bzl
index 8daebc1..9bdcd8c 100644
--- a/third-party/targets.bzl
+++ b/third-party/targets.bzl
@@ -12,6 +12,9 @@ def define_common_targets():
         exported_headers = subdir_glob([
             ("llama.cpp-unicode/include", "*.h"),
         ]),
+        compiler_flags = [
+            "-Wno-error=deprecated-declarations",
+        ],
         visibility = ["@EXECUTORCH_CLIENTS", "//pytorch/tokenizers/..."],
     )