diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 43f91bde8..f456b08a0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -314,6 +314,7 @@ jobs:
             python_action_ver: "3.9"
             simd: sse4.2
             setenvs: export CMAKE_BUILD_TYPE=Debug
+                            CMAKE_VERSION=3.23.0
                             LLVM_VERSION=14.0.0 LLVM_DISTRO_NAME=ubuntu-18.04
                             PUGIXML_VERSION=v1.8
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 79996aefc..11e75f091 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # https://github.com/AcademySoftwareFoundation/OpenShadingLanguage
 
-cmake_minimum_required (VERSION 3.19)
+cmake_minimum_required (VERSION 3.23)
 
 set (OSL_VERSION "1.16.0.0")
 set (OSL_VERSION_OVERRIDE "" CACHE STRING
@@ -30,15 +30,6 @@ else ()
     set (${PROJECT_NAME}_DEV_RELEASE ON)
 endif ()
 
-# Set PROJECT_IS_TOP_LEVEL to ON if if this is the top level project (not
-# if this is included as a subproject of something else). Note that this is
-# handled automatically for CMake >= 3.21.
-if (CMAKE_VERSION VERSION_LESS 3.21)
-    if ("${CMAKE_PROJECT_NAME}" STREQUAL "${PROJECT_NAME}")
-        set (PROJECT_IS_TOP_LEVEL ON)
-    endif ()
-endif ()
-
 # Set up module path for our own cmake modules and add some esential ones
 list (APPEND CMAKE_MODULE_PATH
       "${PROJECT_SOURCE_DIR}/src/cmake/modules"
@@ -83,6 +74,7 @@ message (STATUS "Project install prefix = ${CMAKE_INSTALL_PREFIX}")
 message (STATUS "Configuration types    = ${CMAKE_CONFIGURATION_TYPES}")
 message (STATUS "Build type             = ${CMAKE_BUILD_TYPE}")
 message (STATUS "Supported release      = ${${PROJECT_NAME}_SUPPORTED_RELEASE}")
+message (STATUS "Project is top level   = ${PROJECT_IS_TOP_LEVEL}")
 
 # Make the build area layout look a bit more like the final dist layout
 set (CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
diff --git a/INSTALL.md b/INSTALL.md
index 9960df8b4..462a2e553 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -19,7 +19,7 @@ Dependencies
 OSL requires the following dependencies or tools.
 NEW or CHANGED minimum dependencies since the last major release are **bold**.
 
-* Build system: [CMake](https://cmake.org/) 3.19 or newer (tested
+* Build system: [CMake](https://cmake.org/) 3.23 or newer (tested
   through 4.2)
 
 * A suitable C++17 compiler to build OSL itself, which may be any of: