diff --git a/Makefile b/Makefile
index fd59f14b1..ca4ac9605 100644
--- a/Makefile
+++ b/Makefile
@@ -11,14 +11,13 @@
 
 PYBIND11_VERSION := 2.6.2
 RAPIDJSON_VERSION := 1.1.0
-STAN_VERSION := 2.26.0
-STANC_VERSION := 2.26.0
-MATH_VERSION := 4.0.0
-BOOST_VERSION := 1.72.0
+STAN_VERSION := 2.26.1
+STANC_VERSION := 2.26.1
+MATH_VERSION := 4.0.1
+BOOST_VERSION := 1.75.0
 EIGEN_VERSION := 3.3.9
 SUNDIALS_VERSION := 5.6.1
 TBB_VERSION := 2019_U8
-
 PYBIND11_ARCHIVE := build/archives/pybind11-$(PYBIND11_VERSION).tar.gz
 RAPIDJSON_ARCHIVE := build/archives/rapidjson-$(RAPIDJSON_VERSION).tar.gz
 
diff --git a/httpstan/models.py b/httpstan/models.py
index dca98603f..bd859b4b5 100644
--- a/httpstan/models.py
+++ b/httpstan/models.py
@@ -130,7 +130,7 @@ async def build_services_extension_module(program_code: str, extra_compile_args:
         model_directory_path.as_posix(),
         os.path.join(httpstan_dir, "include"),
         os.path.join(httpstan_dir, "include", "lib", "eigen_3.3.9"),
-        os.path.join(httpstan_dir, "include", "lib", "boost_1.72.0"),
+        os.path.join(httpstan_dir, "include", "lib", "boost_1.75.0"),
         os.path.join(httpstan_dir, "include", "lib", "sundials_5.6.1", "include"),
         os.path.join(httpstan_dir, "include", "lib", "tbb_2019_U8", "include"),
     ]
diff --git a/pyproject.toml b/pyproject.toml
index a285b3356..ac0010f82 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "httpstan"
-version = "4.3.0"
+version = "4.3.1"
 description = "HTTP-based interface to Stan, a package for Bayesian inference."
 authors = [
   "Allen Riddell <riddella@indiana.edu>",