diff --git a/docs/src/developers_guide/contributing_ci_tests.rst b/docs/src/developers_guide/contributing_ci_tests.rst
index 4a7463f903..0257ff7cff 100644
--- a/docs/src/developers_guide/contributing_ci_tests.rst
+++ b/docs/src/developers_guide/contributing_ci_tests.rst
@@ -5,6 +5,10 @@
 Continuous Integration (CI) Testing
 ===================================
 
+.. note:: Iris is currently supported and tested against |python_support|
+          running on Linux.  We do not currently actively test on other
+          platforms such as Windows or macOS.
+
 The `Iris`_ GitHub repository is configured to run checks against all its
 branches automatically whenever a pull-request is created, updated or merged.
 The checks performed are:
diff --git a/docs/src/installing.rst b/docs/src/installing.rst
index 51a0089bdf..e358bb42c9 100644
--- a/docs/src/installing.rst
+++ b/docs/src/installing.rst
@@ -16,7 +16,9 @@ any WSL_ distributions.
 
 .. _WSL: https://docs.microsoft.com/en-us/windows/wsl/install-win10
 
-.. note:: Iris is currently supported and tested against |python_support|.
+.. note:: Iris is currently supported and tested against |python_support|
+          running on Linux.  We do not currently actively test on other
+          platforms such as Windows or macOS.
 
 .. note:: This documentation was built using Python |python_version|.