diff --git a/environment.yml b/environment.yml
index 8233c7ca5..f9766ef2d 100644
--- a/environment.yml
+++ b/environment.yml
@@ -7,8 +7,8 @@ dependencies:
   - pip
   - pip:
     - jupyter-book==0.15.1
-    # - quantecon-book-theme==0.3.2
-    # - sphinx-tojupyter==0.2.1
+    - quantecon-book-theme==0.4.1
+    - sphinx-tojupyter==0.3.0
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==0.4.1
     - sphinx-proof==0.1.3
diff --git a/lectures/_config.yml b/lectures/_config.yml
index b2b926945..d44b9535e 100644
--- a/lectures/_config.yml
+++ b/lectures/_config.yml
@@ -36,7 +36,7 @@ sphinx:
   extra_extensions: [sphinx_multitoc_numbering, sphinxext.rediraffe, sphinx_exercise, sphinx_togglebutton, sphinx_proof] # sphinx_tojupyter
   config:
     html_favicon: _static/lectures-favicon.ico
-    html_theme: sphinx_book_theme
+    html_theme: quantecon_book_theme
     html_static_path: ['_static']
     html_theme_options:
       # header_organisation_url: https://quantecon.org