diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2534c9b..b1b7410 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,12 +2,12 @@
 #
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-cmake_minimum_required(VERSION 3.9)
-if(POLICY CMP0093)
-  cmake_policy(SET CMP0093 NEW) # Use Boost_VERSION x.y.z in CMake >= 3.15 or BoostConfig
+cmake_minimum_required(VERSION 3.16..3.25)
+if(POLICY CMP0177)
+  cmake_policy(SET CMP0177 NEW)  # Normalize install() DESTINATION paths
 endif()
-if (POLICY CMP0074)
-  cmake_policy(SET CMP0074 NEW) # find_package uses <PackageName>_ROOT variables
+if(POLICY CMP0167)
+  cmake_policy(SET CMP0167 OLD)  # FindBoost is removed, keep for now
 endif()
 
 if(NOT RTTR_VERSION)
diff --git a/external/kaguya/CMakeLists.txt b/external/kaguya/CMakeLists.txt
index 694625f..a640a0c 100644
--- a/external/kaguya/CMakeLists.txt
+++ b/external/kaguya/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(CMAKE_LEGACY_CYGWIN_WIN32 0)
-cmake_minimum_required(VERSION 2.6)
+cmake_minimum_required(VERSION 3.16..3.20)
 project(Kaguya)
 
 include(cmake/FindLua.cmake)
@@ -108,4 +108,4 @@ endif(EMSCRIPTEN)
 
 
 enable_testing()
-add_subdirectory(test)
\ No newline at end of file
+add_subdirectory(test)
diff --git a/external/libendian/CMakeLists.txt b/external/libendian/CMakeLists.txt
index 701aeb7..77323b8 100644
--- a/external/libendian/CMakeLists.txt
+++ b/external/libendian/CMakeLists.txt
@@ -1,11 +1,8 @@
-# Copyright (C) 2005 - 2021 Settlers Freaks <sf-team at siedler25.org>
+# Copyright (C) 2005 - 2025 Settlers Freaks <sf-team at siedler25.org>
 #
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-cmake_minimum_required(VERSION 3.8)
-if(POLICY CMP0074)
-    cmake_policy(SET CMP0074 NEW)
-endif()
+cmake_minimum_required(VERSION 3.16..3.20)
 project(libendian)
 
 include(RttrBoostCfg)
diff --git a/external/liblobby/CMakeLists.txt b/external/liblobby/CMakeLists.txt
index 83907e4..897fe32 100644
--- a/external/liblobby/CMakeLists.txt
+++ b/external/liblobby/CMakeLists.txt
@@ -1,8 +1,8 @@
-# Copyright (C) 2005 - 2021 Settlers Freaks <sf-team at siedler25.org>
+# Copyright (C) 2005 - 2025 Settlers Freaks <sf-team at siedler25.org>
 #
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.16..3.20)
 project(liblobby)
 
 set(SOURCES_LOBBY src/LobbyMessage.cpp    include/liblobby/LobbyMessage.h
diff --git a/external/libsiedler2/CMakeLists.txt b/external/libsiedler2/CMakeLists.txt
index 19ff79d..e76b6a3 100644
--- a/external/libsiedler2/CMakeLists.txt
+++ b/external/libsiedler2/CMakeLists.txt
@@ -3,10 +3,8 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 # Project meant to be used as part of a super project including libutil and libendian
-cmake_minimum_required(VERSION 3.9)
-if(POLICY CMP0074)
-    cmake_policy(SET CMP0074 NEW)
-endif()
+cmake_minimum_required(VERSION 3.16..3.20)
+
 project(libsiedler2)
 
 # If top-level project
diff --git a/external/libutil/CMakeLists.txt b/external/libutil/CMakeLists.txt
index 6d6e589..40789ab 100644
--- a/external/libutil/CMakeLists.txt
+++ b/external/libutil/CMakeLists.txt
@@ -1,11 +1,8 @@
-# Copyright (C) 2005 - 2021 Settlers Freaks <sf-team at siedler25.org>
+# Copyright (C) 2005 - 2025 Settlers Freaks <sf-team at siedler25.org>
 #
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-cmake_minimum_required(VERSION 3.8)
-if(POLICY CMP0074)
-    cmake_policy(SET CMP0074 NEW)
-endif()
+cmake_minimum_required(VERSION 3.16..3.20)
 project(s25util)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
diff --git a/external/s25edit/CMakeLists.txt b/external/s25edit/CMakeLists.txt
index 9add4b0..df5ffb0 100644
--- a/external/s25edit/CMakeLists.txt
+++ b/external/s25edit/CMakeLists.txt
@@ -1,9 +1,9 @@
 # Copyright (C) 2009 - 2021 Marc Vester (XaserLE)
-# Copyright (C) 2009 - 2021 Settlers Freaks <sf-team at siedler25.org>
+# Copyright (C) 2009 - 2025 Settlers Freaks <sf-team at siedler25.org>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.16..3.20)
 
 project(s25edit)
 
diff --git a/external/turtle/CMakeLists.txt b/external/turtle/CMakeLists.txt
index 5ddc100..02f5c9e 100644
--- a/external/turtle/CMakeLists.txt
+++ b/external/turtle/CMakeLists.txt
@@ -1,8 +1,8 @@
-# Copyright 2019 Alexander Grund
+# Copyright 2019-2025 Alexander Grund
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.16..3.20)
 project(turtle VERSION 1.3.2 LANGUAGES CXX)
 
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
@@ -67,15 +67,7 @@ if(TURTLE_INSTALL)
     INSTALL_DESTINATION ${configInstallDestination}
   )
 
-  if(NOT CMAKE_VERSION VERSION_LESS 3.14)
-    write_basic_package_version_file(${versionFile} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
-  else()
-    set(OLD_CMAKE_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
-    set(CMAKE_SIZEOF_VOID_P "")
-    write_basic_package_version_file(${versionFile} COMPATIBILITY SameMajorVersion)
-    set(CMAKE_SIZEOF_VOID_P ${OLD_CMAKE_SIZEOF_VOID_P})
-  endif()
-
+  write_basic_package_version_file(${versionFile} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
   install(FILES ${configFile} ${versionFile} DESTINATION ${configInstallDestination})
 
   install(