diff --git a/CMakeLists.txt b/CMakeLists.txt
index f455783ff..e6589e5de 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -106,7 +106,7 @@ if(MAGIC_ENUM_OPT_VERIFY_INTERFACE_HEADER_SETS)
   if(CMAKE_VERSION VERSION_LESS "3.24")
     message(FATAL_ERROR "MAGIC_ENUM_OPT_VERIFY_INTERFACE_HEADER_SETS requires CMake >= 3.24")
   endif()
-  set_property(TARGET ${PROJECT_NAME} PROPERTY VERIFY_INTERFACE_HEADER_SETS ON)
+  set_property(TARGET ${PROJECT_NAME} PROPERTY VERIFY_INTERFACE_HEADER_SETS ${PROJECT_IS_TOP_LEVEL})
 endif()
 
 set(MAGIC_ENUM_MODULE_FMT_TARGET)
@@ -192,7 +192,7 @@ function(magic_enum_make_module_library name)
     endif()
     message(STATUS "${name}: using import std")
     set_property(TARGET ${name} PROPERTY CXX_MODULE_STD ON)
-    target_compile_definitions(${name} PRIVATE MAGIC_ENUM_USE_STD_MODULE)
+    target_compile_definitions(${name} PUBLIC MAGIC_ENUM_USE_STD_MODULE)
   elseif(CMAKE_VERSION VERSION_GREATER_EQUAL "3.31")
     set_property(TARGET ${name} PROPERTY CXX_MODULE_STD OFF)
   endif()
diff --git a/example/CMakeLists.txt b/example/CMakeLists.txt
index 420880c4d..605691f5c 100644
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@@ -45,6 +45,6 @@ if(MAGIC_ENUM_USE_MODULES)
   set_target_properties(example_module_usage PROPERTIES CXX_SCAN_FOR_MODULES ON)
   if(MAGIC_ENUM_MODULE_IMPORT_STD)
     set_property(TARGET example_module_usage PROPERTY CXX_MODULE_STD ON)
-    target_compile_definitions(example_module_usage PRIVATE MAGIC_ENUM_TEST_IMPORT_STD)
+    # XXX target_compile_definitions(example_module_usage PRIVATE MAGIC_ENUM_TEST_IMPORT_STD)
   endif()
 endif()
diff --git a/module/magic_enum.cppm b/module/magic_enum.cppm
index dc3cefb3c..468fb9b6d 100644
--- a/module/magic_enum.cppm
+++ b/module/magic_enum.cppm
@@ -1,12 +1,13 @@
 module;
 
 #include <version>
-#ifdef MAGIC_ENUM_USE_FMT_HEADER
-#  include <fmt/format.h>
-#endif
 
 #ifndef MAGIC_ENUM_USE_STD_MODULE
 
+#  ifdef MAGIC_ENUM_USE_FMT_HEADER
+#    include <fmt/format.h>
+#  endif
+
 #  include <compare>
 #  include <cstdlib>
 #  if __has_include(<format>)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 6ac1d549a..89f68af3a 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -116,7 +116,7 @@ function(magic_enum_make_module_test src target module_target)
       CXX_SCAN_FOR_MODULES ON
   )
   if(MAGIC_ENUM_MODULE_IMPORT_STD)
-    target_compile_definitions(${target} PRIVATE MAGIC_ENUM_TEST_IMPORT_STD)
+    # XXX target_compile_definitions(${target} PRIVATE MAGIC_ENUM_TEST_IMPORT_STD)
     set_property(TARGET ${target} PROPERTY CXX_MODULE_STD ON)
   endif()
   add_test(NAME ${target} COMMAND ${target})
@@ -259,3 +259,42 @@ if(MAGIC_ENUM_USE_MODULES AND MAGIC_ENUM_OPT_INSTALL AND
   )
   set_tests_properties(installed-module-consumer PROPERTIES FIXTURES_REQUIRED magic_enum_installed_module)
 endif()
+
+if(NOT CMAKE_BUILD_TYPE STREQUAL "Release")
+    return()
+endif()
+
+#======================================================================
+# NOTE: Only for Release build with enabled install rules useful! CK
+#======================================================================
+if(MAGIC_ENUM_MODULE_IMPORT_STD AND MAGIC_ENUM_OPT_INSTALL AND NOT CMAKE_SKIP_INSTALL_RULES)
+    # test if the targets are usable from the install directory
+    add_test(
+        NAME install-to-stagedir
+        COMMAND
+            ${CMAKE_COMMAND} --install ${CMAKE_BINARY_DIR} --prefix
+            ${CMAKE_CURRENT_BINARY_DIR}/stagedir --config $<CONFIG>
+    )
+    add_test(
+        NAME find-package-test
+        COMMAND
+            ${CMAKE_CTEST_COMMAND} # --verbose
+            --output-on-failure -C $<CONFIG> #
+            --build-and-test "${CMAKE_SOURCE_DIR}/test/installed_module"
+            "${CMAKE_CURRENT_BINARY_DIR}/find-package-test" #
+            --build-generator ${CMAKE_GENERATOR} #
+            --build-makeprogram ${CMAKE_MAKE_PROGRAM} #
+            --build-options #
+            "-D MAGIC_ENUM_EXPECT_FMT=${MAGIC_ENUM_MODULE_WITH_FMT}"
+            "-D MAGIC_ENUM_EXPECT_FMT_MODULE=${MAGIC_ENUM_MODULE_USES_FMT_MODULE}"
+            "-D MAGIC_ENUM_EXPECT_IMPORT_STD=${MAGIC_ENUM_MODULE_IMPORT_STD}"
+            "-D CMAKE_BUILD_TYPE=$<CONFIG>"
+            "-D CMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}"
+            "-D CMAKE_CXX_EXTENSIONS=${CMAKE_CXX_EXTENSIONS}"
+            "-D CMAKE_CXX_MODULE_STD=${CMAKE_CXX_MODULE_STD}"
+            "-D CMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}"
+            "-D CMAKE_CXX_STANDARD_REQUIRED=${CMAKE_CXX_STANDARD_REQUIRED}"
+            "-D CMAKE_PREFIX_PATH=${CMAKE_CURRENT_BINARY_DIR}/stagedir"
+            "-D CMAKE_EXPERIMENTAL_CXX_IMPORT_STD=${CMAKE_EXPERIMENTAL_CXX_IMPORT_STD}"
+    )
+endif()
diff --git a/test/installed_module/CMakeLists.txt b/test/installed_module/CMakeLists.txt
index 58bfd632b..754291ad7 100644
--- a/test/installed_module/CMakeLists.txt
+++ b/test/installed_module/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.28)
+cmake_minimum_required(VERSION 3.30...4.4)
 
 project(magic_enum_installed_module_test LANGUAGES CXX)
 
diff --git a/test_installed_version.bash b/test_installed_version.bash
new file mode 100644
index 000000000..9daa9a392
--- /dev/null
+++ b/test_installed_version.bash
@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+build_root="${repo_root}/build"
+source_build_dir="${build_root}/source"
+configured_install_dir="${build_root}/configured-install"
+install_dir="${build_root}/install"
+consumer_prefix="${build_root}/relocated-install"
+cmake_consumer_build_dir="${build_root}/cmake-consumer"
+pkgconfig_consumer_build_dir="${build_root}/pkgconfig-consumer"
+cxx_modules_consumer_build_dir="${build_root}/cxx_modules-consumer"
+
+test_installed_consumer() {
+  local build_dir="$1"
+  shift
+
+  CMAKE_PREFIX_PATH="${consumer_prefix}" cmake -S "${repo_root}" -B "${build_dir}" \
+    -G Ninja \
+    -D CMAKE_BUILD_TYPE=Debug \
+    "$@"
+  cmake --build "${build_dir}" --parallel
+  ctest --test-dir "${build_dir}" --output-on-failure --no-tests=error
+}
+
+cmake --version
+cmake -E remove_directory "${build_root}"
+
+cmake -S "${repo_root}" -B "${source_build_dir}" -G Ninja \
+  -D CMAKE_BUILD_TYPE=Release \
+  -D CMAKE_CXX_STANDARD=23 \
+  -D CMAKE_EXPERIMENTAL_CXX_IMPORT_STD=f35a9ac6-8463-4d38-8eec-5d6008153e7d \
+  -D CMAKE_INSTALL_PREFIX="${configured_install_dir}" \
+  -D MAGIC_ENUM_MODULE_IMPORT_STD=YES \
+  -D MAGIC_ENUM_MODULE_WITH_FMT=NO \
+  -D MAGIC_ENUM_OPT_BUILD_EXAMPLES=OFF \
+  -D MAGIC_ENUM_OPT_BUILD_TESTS=YES \
+  -D MAGIC_ENUM_OPT_INSTALL=ON \
+  -D MAGIC_ENUM_OPT_VERIFY_INTERFACE_HEADER_SETS=ON \
+  -D MAGIC_ENUM_USE_MODULES=YES -Wdev --log-level=VERBOSE # XXX --fresh
+cmake --build "${source_build_dir}" \
+  --target magic_enum_verify_interface_header_sets \
+  --parallel
+cmake --build "${source_build_dir}" \
+  --target all \
+  --parallel
+ctest --test-dir "${source_build_dir}" --output-on-failure --no-tests=error
+
+# cmake --install "${source_build_dir}" --prefix "${install_dir}"
+# cmake -E copy_directory "${install_dir}" "${consumer_prefix}"
+
+# test_installed_consumer "${cxx_modules_consumer_build_dir}" \
+#   -D CMAKE_CXX_STANDARD=23 \
+#   -D CMAKE_EXPERIMENTAL_CXX_IMPORT_STD=f35a9ac6-8463-4d38-8eec-5d6008153e7d \
+#   -D MAGIC_ENUM_MODULE_IMPORT_STD=YES \
+#   -D MAGIC_ENUM_MODULE_WITH_FMT=NO \
+#   -D MAGIC_ENUM_OPT_TEST_INSTALLED_VERSION=ON \
+#   -D MAGIC_ENUM_USE_MODULES=YES \
+#   -D PKG_CONFIG_USE_CMAKE_PREFIX_PATH=YES --fresh
+
+# test_installed_consumer "${cmake_consumer_build_dir}" \
+#   -D MAGIC_ENUM_OPT_TEST_INSTALLED_VERSION=ON
+
+# test_installed_consumer "${pkgconfig_consumer_build_dir}" \
+#   -D MAGIC_ENUM_OPT_TEST_INSTALLED_VERSION_PKGCONFIG=ON \
+#   -D PKG_CONFIG_USE_CMAKE_PREFIX_PATH=ON
+