diff --git a/experiments/README.md b/experiments/README.md
index f77e174..a8d2448 100644
--- a/experiments/README.md
+++ b/experiments/README.md
@@ -107,7 +107,7 @@ Next, we will run NNSmith to dump a bunch of random test-cases for an SUT (say P
 >
 > ```shell
 > # PyTorch
-> pip install --extra-index-url https://download.pytorch.org/whl/nightly/cpu --pre torch
+> pip install --index-url https://download.pytorch.org/whl/nightly/cpu --pre torch
 > # TensorFlow
 > pip install tf-nightly
 > ```
diff --git a/requirements/sys/torch.txt b/requirements/sys/torch.txt
index cf4fc37..1dfee20 100644
--- a/requirements/sys/torch.txt
+++ b/requirements/sys/torch.txt
@@ -1,4 +1,4 @@
 # TODO(@ganler): make other platform/device distribution also work.
---extra-index-url https://download.pytorch.org/whl/nightly/cpu
+--index-url https://download.pytorch.org/whl/nightly/cpu
 --pre
 torch