diff --git a/.readthedocs.yml b/.readthedocs.yaml
similarity index 76%
rename from .readthedocs.yml
rename to .readthedocs.yaml
index bb51713..3daf865 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yaml
@@ -1,4 +1,4 @@
-# .readthedocs.yml
+# .readthedocs.yaml
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
 
@@ -7,7 +7,9 @@ version: 2
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
+  builder: html
   configuration: docs/source/conf.py
+  fail_on_warning: false
 
 # Build documentation with MkDocs
 #mkdocs:
@@ -16,9 +18,16 @@ sphinx:
 # Optionally build your docs in additional formats such as PDF and ePub
 formats: all
 
+build:
+  os: ubuntu-24.04
+  tools:
+    python: mambaforge-latest
+
+conda:
+  environment: docs/rtd_environment.yaml
+
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.7
   install:
     - method: pip
       path: .
diff --git a/costools/timefilter.py b/costools/timefilter.py
index 49b7d0b..02aaad1 100755
--- a/costools/timefilter.py
+++ b/costools/timefilter.py
@@ -224,7 +224,7 @@ def toRect(longitude, latitude):
         latitude in degrees.
 
     Returns
-    --------
+    -------
     array_like
         Unit vector in rectangular coordinates.
     """
diff --git a/docs/rtd_environment.yaml b/docs/rtd_environment.yaml
new file mode 100644
index 0000000..0bdfcca
--- /dev/null
+++ b/docs/rtd_environment.yaml
@@ -0,0 +1,6 @@
+channels:
+ - conda-forge
+dependencies:
+ - python=3.13
+ - pip
+ - graphviz
diff --git a/docs/source/conf.py b/docs/source/conf.py
index e36b0b1..c553771 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -208,3 +208,6 @@
 
 # If false, no module index is generated.
 #latex_use_modindex = True
+
+# Enable nitpicky mode - which ensures that all references in the docs resolve.
+nitpicky = True
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 7db4573..0f06371 100755
--- a/setup.py
+++ b/setup.py
@@ -19,6 +19,7 @@
         'docs': [
             'sphinx',
             'numpydoc',
+            'sphinx_rtd_theme>1.2.0',
         ],
         'test': [
             'pytest',