diff --git a/CMakeLists.txt b/CMakeLists.txt
index cd04117..91d969c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,7 +5,7 @@
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-cmake_minimum_required( VERSION 3.5 FATAL_ERROR )
+cmake_minimum_required( VERSION 3.15 FATAL_ERROR )
 
 # expected-lite project and version, updated by script/update-version.py:
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 489b93a..20b5a2f 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -6,7 +6,7 @@
 # (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 if( NOT DEFINED CMAKE_MINIMUM_REQUIRED_VERSION )
-    cmake_minimum_required( VERSION 3.5 FATAL_ERROR )
+    cmake_minimum_required( VERSION 3.15 FATAL_ERROR )
 endif()
 
 project( test LANGUAGES CXX )