diff --git a/.gitmodules b/.gitmodules
index 9258685..5cabeb7 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -54,3 +54,7 @@
 	path = book/external/sphinx-iframes
 	url = https://github.com/TeachBooks/sphinx-iframes.git
 	branch = manual
+[submodule "book/external/Sphinx-PRIME-applets"]
+	path = book/external/Sphinx-PRIME-applets
+	url = https://github.com/TeachBooks/Sphinx-PRIME-applets.git
+	branch = manual
diff --git a/book/_config.yml b/book/_config.yml
index c8d247f..03274cc 100644
--- a/book/_config.yml
+++ b/book/_config.yml
@@ -22,6 +22,7 @@ sphinx:
   - sphinx_proof
   - sphinx_named_colors
   - sphinx_iframes
+  - sphinx_prime_applets
   config:
     html_js_files:
     - https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.4/require.min.js
diff --git a/book/_toc.yml b/book/_toc.yml
index d745c73..d8702be 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -77,6 +77,7 @@ parts:
         - file: features/widgets.ipynb
         - file: features/exercise_checking.ipynb
       - file: external/sphinx-iframes/README.md
+      - file: external/Sphinx-PRIME-applets/README.md
     - file: features/visuals.md
       sections:
       - file: external/Sphinx-Image-Inverter/README.md
diff --git a/book/external/Sphinx-PRIME-applets b/book/external/Sphinx-PRIME-applets
new file mode 160000
index 0000000..43ea44c
--- /dev/null
+++ b/book/external/Sphinx-PRIME-applets
@@ -0,0 +1 @@
+Subproject commit 43ea44ccdc917234513fcd0ea1b9d5159a7dc81f
diff --git a/requirements.txt b/requirements.txt
index d196a01..25a3325 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,7 +7,8 @@ sphinx-image-inverter == 1.1.2
 sphinx-exercise == 1.0.1
 sphinx-proof == 0.2.0
 sphinx-named-colors == 1.0.1
-sphinx-iframes
+sphinx-iframes == 1.0.1
+sphinx-prime-applets == 1.0.1
 
 git+https://github.com/TeachBooks/Sphinx-Thebe