diff --git a/crates/ctranslate2-bindings/src/lib.rs b/crates/ctranslate2-bindings/src/lib.rs
index 2a61337..01f57b3 100644
--- a/crates/ctranslate2-bindings/src/lib.rs
+++ b/crates/ctranslate2-bindings/src/lib.rs
@@ -124,21 +124,10 @@ impl TextInferenceEngine {
         } else {
             let mut re = self.stop_regex_cache.get(options.stop_words);
             if re.is_none() {
-                let encodings = self
-                    .tokenizer
-                    .encode_batch(options.stop_words.clone(), false)
-                    .unwrap();
-                let stop_tokens: Vec<String> = encodings
-                    .iter()
-                    .map(|x| x.get_tokens().join(""))
-                    // Reverse for efficient suffix matching.
-                    .map(reverse)
-                    .collect();
-
-                // \A means absolute begins of string.
-                let regex_string = r"(?m)\A".to_owned() + &stop_tokens.join("|");
-                let regex = Regex::new(&regex_string).unwrap();
-                self.stop_regex_cache.insert(options.stop_words, regex);
+                self.stop_regex_cache.insert(
+                    options.stop_words,
+                    create_stop_regex(&self.tokenizer, options.stop_words),
+                );
                 re = self.stop_regex_cache.get(options.stop_words);
             }
             re.map(|x| x.value().clone())
@@ -182,3 +171,17 @@ fn inference_callback(
 fn reverse(s: String) -> String {
     s.chars().rev().collect()
 }
+
+fn create_stop_regex(tokenizer: &Tokenizer, stop_words: &Vec<&str>) -> Regex {
+    let encodings = tokenizer.encode_batch(stop_words.clone(), false).unwrap();
+    let stop_tokens: Vec<String> = encodings
+        .iter()
+        .map(|x| x.get_tokens().join(""))
+        // Reverse for efficient suffix matching.
+        .map(reverse)
+        .collect();
+
+    // \A means absolute begins of string.
+    let regex_string = r"(?m)\A".to_owned() + &stop_tokens.join("|");
+    Regex::new(&regex_string).unwrap()
+}