diff --git a/requirements-dev.txt b/requirements-dev.txt
index 2877c2bba6..93763a9611 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -10,6 +10,5 @@ pytest
 pytest-cov
 scikit-learn
 scipy
-six
 sympy
 wheel
diff --git a/requirements.txt b/requirements.txt
index 882788d812..52a73514b6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,3 @@
 numpy >= 1.18.0
 onnx >= 1.2.3
 protobuf
-six