diff --git a/KF5CoreAddonsMacros.cmake b/KF5CoreAddonsMacros.cmake
--- a/KF5CoreAddonsMacros.cmake
+++ b/KF5CoreAddonsMacros.cmake
@@ -138,6 +138,11 @@
 
     add_library(${plugin} MODULE ${KCA_ADD_PLUGIN_SOURCES})
     set_property(TARGET ${plugin} APPEND PROPERTY AUTOGEN_TARGET_DEPENDS ${json})
+    # If find_package(ECM 5.38) or higher is called, output the plugin in a INSTALL_NAMESPACE subfolder.
+    # See https://community.kde.org/Guidelines_and_HOWTOs/Making_apps_run_uninstalled
+    if(NOT ("${ECM_GLOBAL_FIND_VERSION}" VERSION_LESS "5.38.0"))
+        set_target_properties(${plugin} PROPERTIES LIBRARY_OUTPUT_DIRECTORY "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${KCA_ADD_PLUGIN_INSTALL_NAMESPACE}")
+    endif()
 
     if (NOT KCA_ADD_PLUGIN_INSTALL_NAMESPACE)
         message(FATAL_ERROR "Must specify INSTALL_NAMESPACE for ${plugin}")