diff --git a/lectures/input_output.md b/lectures/input_output.md
index 04959b5e..320345ed 100644
--- a/lectures/input_output.md
+++ b/lectures/input_output.md
@@ -20,7 +20,7 @@ This lecture requires the following imports and installs before we proceed.
 ```{code-cell} ipython3
 :tags: [hide-output]
 
-!pip install quantecon_book_networks
+!pip install quantecon_book_networks==1.6
 !pip install quantecon
 !pip install pandas-datareader
 ```
diff --git a/lectures/networks.md b/lectures/networks.md
index 25943982..c5866b97 100644
--- a/lectures/networks.md
+++ b/lectures/networks.md
@@ -16,7 +16,7 @@ kernelspec:
 ```{code-cell} ipython3
 :tags: [hide-output]
 
-!pip install quantecon-book-networks pandas-datareader
+!pip install quantecon-book-networks==1.6 pandas-datareader
 ```
 
 ## Outline