diff --git a/cmake/findDependencies.cmake b/cmake/findDependencies.cmake
index da6d639755ed..8219e36bd36a 100644
--- a/cmake/findDependencies.cmake
+++ b/cmake/findDependencies.cmake
@@ -24,6 +24,7 @@ if (BUILD_GUI)
             set(DISABLE_CRTDBG_MAP_ALLOC ON)
         endif()
     else()
+        message(WARNING "Building with Qt5 is deprecated (it went EOL in May 2023) and will be removed in a future release - please use Qt6 instead")
         find_package(Qt5 COMPONENTS ${qt_components} REQUIRED)
         set(QT_VERSION "${Qt5Core_VERSION_STRING}")
     endif()
diff --git a/releasenotes.txt b/releasenotes.txt
index 9967518840f3..936dbf45435d 100644
--- a/releasenotes.txt
+++ b/releasenotes.txt
@@ -12,6 +12,9 @@ GUI:
 Changed interface:
 -
 
+Deprecations:
+- Building with Qt5 has been deprecated (it went EOL in May 2023) and will be removed in a future version - please use Qt6 instead.
+
 Other:
 - Windows builds now default to the `native` platform instead of `win32A` or `win64`. Please specify it explicitly if you depedent on it.
 - The undocumented and deprecated command-line options `--template <template>` and `--template-format <template>` has been removed. Please use `--template=` and `--template-format=` instead.
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