diff --git a/cmake/install.cmake b/cmake/install.cmake
index d071b15..f7fa5bf 100644
--- a/cmake/install.cmake
+++ b/cmake/install.cmake
@@ -49,6 +49,7 @@
     install(FILES       ${INTERFACE_INC_DIR}/multi_core/tfm_multi_core_api.h
                         ${INTERFACE_INC_DIR}/multi_core/tfm_ns_mailbox.h
                         ${INTERFACE_INC_DIR}/multi_core/tfm_mailbox.h
+                        ${INTERFACE_INC_DIR}/multi_core/tfm_ns_mailbox_test.h
                         ${CMAKE_BINARY_DIR}/generated/interface/include/tfm_mailbox_config.h
             DESTINATION ${INSTALL_INTERFACE_INC_DIR})
 elseif (NOT TFM_PSA_API)