diff --git a/CMakeLists.txt b/CMakeLists.txt
index c59c9042c..8380f6113 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -240,6 +240,9 @@ if(GPERF)
   endif()
 endif()
 
+# Despite setting C++ standard to 20, features from this version are not being used.
+# The oldest compiler used is GCC 6.5 - and that defines our C++ feature set (meaning most of C++17).
+# It's present only to take advantage of fmt::format build time errors.
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_CXX_STANDARD_REQUIRED OFF)
diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index b2eabb4ee..e37655b1f 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -3,6 +3,11 @@
 This guide outlines useful resources, tools and processes for contribution to
 DevilutionX.
 
+## C++ Standard
+Despite setting C++ standard to 20 in CMakeLists.txt, features from this version are not being used.
+The oldest compiler used is GCC 6.5 - and that defines our C++ feature set (meaning most of C++17).
+It's present only to take advantage of fmt::format build time errors.
+
 ## Code style guide
 
 [The code style guide](https://github.com/diasurgical/devilutionX/wiki/Code-Style) is evolving with the project.