diff --git a/envs/environment-dev.yaml b/envs/environment-dev.yaml
index 3b9c6e9d..0294e0d9 100644
--- a/envs/environment-dev.yaml
+++ b/envs/environment-dev.yaml
@@ -92,9 +92,9 @@ dependencies:
   - tomli
 
   # For documentation
-  - sphinx
-  - sphinx_rtd_theme=1.2
-  - sphinx-notfound-page
+  - sphinx=5.3.0
+  - sphinx-notfound-page=1.0.0
+  - sphinx-rtd-theme=1.3.0
 
   # For exploration
 #  - ipython
diff --git a/envs/environment-fig-dev.yaml b/envs/environment-fig-dev.yaml
index 6c2b4579..340387a3 100644
--- a/envs/environment-fig-dev.yaml
+++ b/envs/environment-fig-dev.yaml
@@ -69,9 +69,9 @@ dependencies:
   - jupyterlab
 
   # For documentation
-  - sphinx
-  - sphinx_rtd_theme=1.2
-  - sphinx-notfound-page
+  - sphinx=5.3.0
+  - sphinx-notfound-page=1.0.0
+  - sphinx-rtd-theme=1.3.0
 
   - pip:
     - angles
diff --git a/envs/environment-linkcheck.yaml b/envs/environment-linkcheck.yaml
index ec0bc1cf..b2d47e5c 100644
--- a/envs/environment-linkcheck.yaml
+++ b/envs/environment-linkcheck.yaml
@@ -66,9 +66,9 @@ dependencies:
   - xarray
 
   # For documentation links checking
-  - sphinx
-  - sphinx_rtd_theme=1.2
-  - sphinx-notfound-page
+  - sphinx=5.3.0
+  - sphinx-notfound-page=1.0.0
+  - sphinx-rtd-theme=1.3.0
 
   - pip:
     - angles
diff --git a/envs/environment-rtd.yaml b/envs/environment-rtd.yaml
index e13f3e39..dfd475b8 100644
--- a/envs/environment-rtd.yaml
+++ b/envs/environment-rtd.yaml
@@ -15,10 +15,19 @@ dependencies:
   - python=3.12
   - retrying
 
-  # RTD packages
+  # Sphinx and extensions
+  - sphinx=5.3.0
+  - sphinx-notfound-page=1.0.0
+  - sphinx-rtd-theme=1.3.0
+
+  # readthedocs build system packages
   - mock
   - pillow
   - pip:
+    - commonmark
+    - recommonmark
+    - readthedocs-sphinx-ext
+
     # Install NEMO_Nowcast and SalishSeaNowcast packages in editable mode
     - --editable git+https://github.com/43ravens/NEMO_Nowcast.git#egg=NEMO_Nowcast
     - --editable ../