diff --git a/pyproject.toml b/pyproject.toml
index ed6f6dc..ca77e23 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,6 +27,7 @@ dependencies = [
     "g2p_en",
     "jieba",
     "loguru",
+    "nltk<=3.8.1",
     "num2words",
     "numba",
     "numpy",
diff --git a/requirements-colab.txt b/requirements-colab.txt
index 7199118..facd9e1 100644
--- a/requirements-colab.txt
+++ b/requirements-colab.txt
@@ -6,6 +6,7 @@ gradio>=4.32
 jieba
 librosa==0.9.2
 loguru
+nltk<=3.8.1
 num2words
 numpy<2
 onnxruntime
diff --git a/requirements-infer.txt b/requirements-infer.txt
index 30ced75..0fd1a63 100644
--- a/requirements-infer.txt
+++ b/requirements-infer.txt
@@ -8,6 +8,7 @@ gradio>=4.32
 jieba
 # librosa==0.9.2
 loguru
+nltk<=3.8.1
 num2words
 numpy<2
 onnxruntime
diff --git a/requirements.txt b/requirements.txt
index 4e0a084..475ca5c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,6 +8,7 @@ gradio>=4.32
 jieba
 librosa==0.9.2
 loguru
+nltk<=3.8.1
 num2words
 numpy<2
 onnxruntime