diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 47fd113..e8186b8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,11 +10,9 @@ jobs:
     strategy:
       matrix:
         include:
-          - {runs-on: ubuntu-20.04, python-version: "3.8"}
           - {runs-on: ubuntu-20.04, python-version: "3.9"}
           - {runs-on: ubuntu-22.04, python-version: "3.10"}
           - {runs-on: ubuntu-22.04, python-version: "3.11"}
-          - {runs-on: macos-11, python-version: "3.8"}
           - {runs-on: macos-11, python-version: "3.9"}
           - {runs-on: macos-11, python-version: "3.10"}
           - {runs-on: macos-11, python-version: "3.11"}
diff --git a/docs-requirements.txt b/docs-requirements.txt
index 3352d78..91d83eb 100644
--- a/docs-requirements.txt
+++ b/docs-requirements.txt
@@ -1,5 +1,5 @@
 # docs requirements
 # these requirements are used by the documentation builder
 
-sphinx~=4.2 # BSD
-sphinx-rtd-theme~=1.0.0
+sphinx~=7.2 # BSD
+sphinx-rtd-theme~=2.0
diff --git a/pyproject.toml b/pyproject.toml
index 0dbd635..bc8ccf3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pystan"
-version = "3.8.0"
+version = "3.9.0"
 description = "Python interface to Stan, a package for Bayesian inference"
 authors = [
   "Allen Riddell <riddella@indiana.edu>",
@@ -22,9 +22,9 @@ classifiers = [
 ]
 
 [tool.poetry.dependencies]
-python = "^3.8"
+python = "^3.9"
 aiohttp = "^3.6"
-httpstan = "~4.11"
+httpstan = "~4.12"
 pysimdjson = "^5.0.2"
 numpy = "^1.19"
 clikit = "^0.6"
@@ -42,8 +42,8 @@ types-setuptools = "^57.4"
 flake8 = "^4.0"
 # documentation
 # NOTE: when changing these, update docs-requirements.txt
-sphinx = "^4.2"
-sphinx-rtd-theme = "^1.0"
+sphinx = "^7.2"
+sphinx-rtd-theme = "^2.0"
 
 [tool.black]
 line-length = 119
diff --git a/stan/fit.py b/stan/fit.py
index d9176fd..3dda627 100644
--- a/stan/fit.py
+++ b/stan/fit.py
@@ -52,7 +52,7 @@ def __init__(
         # These names are gathered later in this function by inspecting the output from Stan.
         self.sample_and_sampler_param_names: Tuple[str, ...]
 
-        num_flat_params = sum(np.product(dims_ or 1) for dims_ in dims)  # if dims == [] then it is a scalar
+        num_flat_params = sum(np.prod(dims_ or 1) for dims_ in dims)  # if dims == [] then it is a scalar
         assert num_flat_params == len(constrained_param_names)
         num_samples_saved = ceil(self.num_samples / self.num_thin) + ceil(
             (self.num_warmup * self.save_warmup) / self.num_thin