diff --git a/.github/workflows/ci_tests.yml b/.github/workflows/ci_tests.yml
index 5e69f84..98fd751 100644
--- a/.github/workflows/ci_tests.yml
+++ b/.github/workflows/ci_tests.yml
@@ -26,16 +26,16 @@ jobs:
             python: 3.x
             toxenv: codestyle
 
-          - name: Python 3.9 with minimal dependencies
+          - name: Python 3.11 with minimal dependencies
             os: ubuntu-latest
-            python: 3.9
-            toxenv: py39-test
+            python: 3.11
+            toxenv: py311-test
             toxposargs: --remote-data=none
 
-          - name: Python 3.9 with latest dev versions of key dependencies
+          - name: Python 3.11 with latest dev versions of key dependencies
             os: ubuntu-latest
-            python: 3.9
-            toxenv: py39-test-devdeps
+            python: 3.11
+            toxenv: py311-test-devdeps
             toxposargs: --remote-data=none
 
           - name: Test building of Sphinx docs
diff --git a/.readthedocs.yml b/.readthedocs.yml
index aec633e..66db6ce 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -3,11 +3,8 @@ version: 2
 build:
   image: latest
 
-conda:
-  environment: environment.yml
-
 python:
-  version: 3.8
+  version: 3.11
   install:
     - method: pip
       path: .
diff --git a/environment.yml b/environment.yml
index 622527f..5f4a2a1 100644
--- a/environment.yml
+++ b/environment.yml
@@ -1,13 +1,2 @@
 name: gadfly
-channels:
-  - astropy
-dependencies:
-  - astropy
-  - pip:
-    - pytest-astropy
-    - celerite2
-    - matplotlib
-    - PyYAML
-    - scipy
-    - lightkurve
-    - tynt
+
diff --git a/setup.cfg b/setup.cfg
index 9f5e3d3..cbd3561 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -11,7 +11,7 @@ long_description = file: README.rst
 [options]
 zip_safe = False
 packages = find:
-python_requires = >=3.8
+python_requires = >=3.9
 setup_requires = setuptools_scm
 install_requires =
     numpy
diff --git a/tox.ini b/tox.ini
index 5af320b..ecb5b93 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{37,38,39}-test{,-alldeps,-devdeps}
+    py{311,312}-test{,-alldeps,-devdeps}
     build_docs
     codestyle
 isolated_build = true
@@ -32,10 +32,8 @@ description =
     alldeps: with all optional dependencies
     devdeps: with the latest developer version of key dependencies
 deps =
-    astropy50: astropy==5.0.*
-
-    devdeps: git+https://github.com/numpy/numpy.git#egg=numpy
     devdeps: git+https://github.com/astropy/astropy.git#egg=astropy
+    devdeps: git+https://github.com/exoplanet-dev/celerite2#egg=celerite2
 
     numpy
     astropy