diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7f28c5f3..d192e03d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,10 +1,13 @@
 cmake_minimum_required(VERSION 3.7)
 
-project(SoftEtherVPN
+project("SoftEther VPN"
   VERSION 5.01.9664
   LANGUAGES C
 )
 
+set(TOP_DIRECTORY ${CMAKE_SOURCE_DIR})
+set(BUILD_DIRECTORY ${TOP_DIRECTORY}/build)
+
 # We define a dedicated variable because CMAKE_BUILD_TYPE can have different
 # configurations than "Debug" and "Release", such as "RelWithDebInfo".
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
@@ -14,12 +17,12 @@ else()
 endif()
 
 # Check that submodules are present only if source was downloaded with git
-if(EXISTS "${SoftEtherVPN_SOURCE_DIR}/.git" AND NOT EXISTS "${SoftEtherVPN_SOURCE_DIR}/src/Mayaqua/3rdparty/cpu_features/CMakeLists.txt")
+if(EXISTS "${TOP_DIRECTORY}/.git" AND NOT EXISTS "${TOP_DIRECTORY}/src/Mayaqua/3rdparty/cpu_features/CMakeLists.txt")
     message (FATAL_ERROR "Submodules are not initialized. Run\n\tgit submodule update --init --recursive")
 endif()
 
 # Compare ${PROJECT_VERSION} and src/CurrentBuild.txt
-file(READ ${SoftEtherVPN_SOURCE_DIR}/src/CurrentBuild.txt CurrentBuild)
+file(READ ${TOP_DIRECTORY}/src/CurrentBuild.txt CurrentBuild)
 
 string(REGEX MATCH "VERSION_MAJOR ([0-9]+)" temp ${CurrentBuild})
 string(REGEX REPLACE "VERSION_MAJOR ([0-9]+)" "\\1" CurrentBuild_MAJOR ${temp})
@@ -40,9 +43,8 @@ if(UNIX)
   Check_Include_File(sys/auxv.h HAVE_SYS_AUXV)
 endif()
 
-configure_file("${SoftEtherVPN_SOURCE_DIR}/AUTHORS.TXT" "${SoftEtherVPN_SOURCE_DIR}/src/bin/hamcore/authors.txt" COPYONLY)
+configure_file("${TOP_DIRECTORY}/AUTHORS.TXT" "${TOP_DIRECTORY}/src/bin/hamcore/authors.txt" COPYONLY)
 
-set(BUILD_DIRECTORY ${SoftEtherVPN_SOURCE_DIR}/build)
 set(CPACK_PACKAGING_INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX})
 
 add_subdirectory(src)
@@ -54,11 +56,11 @@ if(UNIX)
   set(CPACK_PACKAGE_VERSION ${PROJECT_VERSION})
   set(CPACK_PACKAGE_VENDOR "SoftEther")
   set(CPACK_PACKAGE_NAME "softether")
-  set(CPACK_PACKAGE_DESCRIPTION_FILE "${SoftEtherVPN_SOURCE_DIR}/description")
+  set(CPACK_PACKAGE_DESCRIPTION_FILE "${TOP_DIRECTORY}/description")
   set(CPACK_PACKAGE_DESCRIPTION_SUMMARY "SoftEther VPN is an open-source cross-platform multi-protocol VPN program, created as an academic project in the University of Tsukuba.")
 
   # DEB
-  if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+  if(BUILD_TYPE STREQUAL "Debug")
     set(CPACK_DEBIAN_PACKAGE_DEBUG ON)
   endif()
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f63de397..9f34aa06 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -4,11 +4,11 @@ if(UNIX)
   macro(install_wrapper_script component target)
     get_filename_component(file_name ${target} NAME)
 
-    file(WRITE ${CMAKE_SOURCE_DIR}/tmp/script/${file_name} "#!/bin/sh\n")
-    file(APPEND ${CMAKE_SOURCE_DIR}/tmp/script/${file_name} "${target} \"$@\"\n")
-    file(APPEND ${CMAKE_SOURCE_DIR}/tmp/script/${file_name} "exit $?\n")
+    file(WRITE ${TOP_DIRECTORY}/tmp/script/${file_name} "#!/bin/sh\n")
+    file(APPEND ${TOP_DIRECTORY}/tmp/script/${file_name} "${target} \"$@\"\n")
+    file(APPEND ${TOP_DIRECTORY}/tmp/script/${file_name} "exit $?\n")
 
-    install(FILES ${CMAKE_SOURCE_DIR}/tmp/script/${file_name}
+    install(FILES ${TOP_DIRECTORY}/tmp/script/${file_name}
       COMPONENT ${component}
       DESTINATION ${CMAKE_INSTALL_FULL_BINDIR}
       PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE
@@ -100,7 +100,7 @@ add_subdirectory(vpntest)
 # hamcore.se2 archive file
 add_custom_target(hamcore-archive-build
   ALL
-  COMMAND hamcorebuilder "${CMAKE_SOURCE_DIR}/src/bin/hamcore/" "${BUILD_DIRECTORY}/hamcore.se2"
+  COMMAND hamcorebuilder "${TOP_DIRECTORY}/src/bin/hamcore/" "${BUILD_DIRECTORY}/hamcore.se2"
   DEPENDS hamcorebuilder
   COMMENT "Building hamcore.se2 archive file..."
   VERBATIM
diff --git a/src/Mayaqua/CMakeLists.txt b/src/Mayaqua/CMakeLists.txt
index 2c6f84a7..8d1837e4 100644
--- a/src/Mayaqua/CMakeLists.txt
+++ b/src/Mayaqua/CMakeLists.txt
@@ -31,22 +31,22 @@ if(WIN32)
   if(${COMPILER_ARCHITECTURE} STREQUAL "x64")
     find_library(LIB_SSL
       NAMES libssl ssleay32
-      HINTS "${CMAKE_SOURCE_DIR}/src/BuildFiles/Library/vs2017/x64_${BUILD_TYPE}"
+      HINTS "${TOP_DIRECTORY}/src/BuildFiles/Library/vs2017/x64_${BUILD_TYPE}"
     )
 
     find_library(LIB_CRYPTO
       NAMES libcrypto libeay32
-      HINTS "${CMAKE_SOURCE_DIR}/src/BuildFiles/Library/vs2017/x64_${BUILD_TYPE}"
+      HINTS "${TOP_DIRECTORY}/src/BuildFiles/Library/vs2017/x64_${BUILD_TYPE}"
     )
   else()
     find_library(LIB_SSL
       NAMES libssl ssleay32
-      HINTS "${CMAKE_SOURCE_DIR}/src/BuildFiles/Library/vs2017/Win32_${BUILD_TYPE}"
+      HINTS "${TOP_DIRECTORY}/src/BuildFiles/Library/vs2017/Win32_${BUILD_TYPE}"
     )
 
     find_library(LIB_CRYPTO
       NAMES libcrypto libeay32
-      HINTS "${CMAKE_SOURCE_DIR}/src/BuildFiles/Library/vs2017/Win32_${BUILD_TYPE}"
+      HINTS "${TOP_DIRECTORY}/src/BuildFiles/Library/vs2017/Win32_${BUILD_TYPE}"
     )
   endif()
 
diff --git a/src/PenCore/CMakeLists.txt b/src/PenCore/CMakeLists.txt
index eb579b47..5cb3175c 100644
--- a/src/PenCore/CMakeLists.txt
+++ b/src/PenCore/CMakeLists.txt
@@ -6,9 +6,9 @@ add_library(PenCore SHARED pencore.c pencore.rc)
 
 set_target_properties(PenCore
   PROPERTIES
-  ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/src/bin/hamcore"
-  LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/src/bin/hamcore"
-  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/src/bin/hamcore"
+  ARCHIVE_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/src/bin/hamcore"
+  LIBRARY_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/src/bin/hamcore"
+  RUNTIME_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/src/bin/hamcore"
   PDB_OUTPUT_DIRECTORY "${BUILD_DIRECTORY}"
 )
 
diff --git a/src/hamcorebuilder/CMakeLists.txt b/src/hamcorebuilder/CMakeLists.txt
index 7a25e5c8..3e8d7b3d 100644
--- a/src/hamcorebuilder/CMakeLists.txt
+++ b/src/hamcorebuilder/CMakeLists.txt
@@ -2,15 +2,15 @@ add_executable(hamcorebuilder hamcorebuilder.c)
 
 set_target_properties(hamcorebuilder
   PROPERTIES
-  ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/tmp"
-  LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/tmp"
-  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/tmp"
+  ARCHIVE_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/tmp"
+  LIBRARY_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/tmp"
+  RUNTIME_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/tmp"
 )
 
 if(WIN32)
   set_target_properties(hamcorebuilder
     PROPERTIES
-    PDB_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/tmp"
+    PDB_OUTPUT_DIRECTORY "${TOP_DIRECTORY}/tmp"
   )
 endif()
 
diff --git a/src/vpnbridge/CMakeLists.txt b/src/vpnbridge/CMakeLists.txt
index b57f4d83..7f9ccc2d 100644
--- a/src/vpnbridge/CMakeLists.txt
+++ b/src/vpnbridge/CMakeLists.txt
@@ -38,7 +38,7 @@ if(UNIX)
 
   install_wrapper_script("vpnbridge" "${CMAKE_INSTALL_FULL_LIBEXECDIR}/softether/vpnbridge/vpnbridge")
   if(EXISTS "/lib/systemd/system")
-    configure_file(${CMAKE_SOURCE_DIR}/systemd/softether-vpnbridge.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnbridge.service)
+    configure_file(${TOP_DIRECTORY}/systemd/softether-vpnbridge.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnbridge.service)
     install(FILES ${CMAKE_BINARY_DIR}/systemd/softether-vpnbridge.service
       COMPONENT "vpnbridge"
       DESTINATION "/lib/systemd/system"
diff --git a/src/vpnclient/CMakeLists.txt b/src/vpnclient/CMakeLists.txt
index abf82ad2..709bd441 100644
--- a/src/vpnclient/CMakeLists.txt
+++ b/src/vpnclient/CMakeLists.txt
@@ -38,7 +38,7 @@ if(UNIX)
 
   install_wrapper_script("vpnclient" "${CMAKE_INSTALL_FULL_LIBEXECDIR}/softether/vpnclient/vpnclient")
   if(EXISTS "/lib/systemd/system")
-    configure_file(${CMAKE_SOURCE_DIR}/systemd/softether-vpnclient.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnclient.service)
+    configure_file(${TOP_DIRECTORY}/systemd/softether-vpnclient.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnclient.service)
     install(FILES ${CMAKE_BINARY_DIR}/systemd/softether-vpnclient.service
       COMPONENT "vpnclient"
       DESTINATION "/lib/systemd/system"
diff --git a/src/vpncmgr/CMakeLists.txt b/src/vpncmgr/CMakeLists.txt
index 9d4aa7be..4b899338 100644
--- a/src/vpncmgr/CMakeLists.txt
+++ b/src/vpncmgr/CMakeLists.txt
@@ -5,9 +5,9 @@ endif()
 set(VPNCMGR_SOURCES vpncmgr.c vpncmgr.rc)
 
 if(${COMPILER_ARCHITECTURE} STREQUAL "x64")
-  set(VPNCMGR_SOURCES ${VPNCMGR_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x64_user.manifest)
+  set(VPNCMGR_SOURCES ${VPNCMGR_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x64_user.manifest)
 else()
-  set(VPNCMGR_SOURCES ${VPNCMGR_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x86_user.manifest)
+  set(VPNCMGR_SOURCES ${VPNCMGR_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x86_user.manifest)
 endif()
 
 add_executable(vpncmgr WIN32 ${VPNCMGR_SOURCES})
diff --git a/src/vpnserver/CMakeLists.txt b/src/vpnserver/CMakeLists.txt
index 81c4eb6c..7841a0a9 100644
--- a/src/vpnserver/CMakeLists.txt
+++ b/src/vpnserver/CMakeLists.txt
@@ -38,7 +38,7 @@ if(UNIX)
 
   install_wrapper_script("vpnserver" "${CMAKE_INSTALL_FULL_LIBEXECDIR}/softether/vpnserver/vpnserver")
   if(EXISTS "/lib/systemd/system")
-    configure_file(${CMAKE_SOURCE_DIR}/systemd/softether-vpnserver.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnserver.service)
+    configure_file(${TOP_DIRECTORY}/systemd/softether-vpnserver.service ${CMAKE_BINARY_DIR}/systemd/softether-vpnserver.service)
     install(FILES ${CMAKE_BINARY_DIR}/systemd/softether-vpnserver.service
       COMPONENT "vpnserver"
       DESTINATION "/lib/systemd/system"
diff --git a/src/vpnsmgr/CMakeLists.txt b/src/vpnsmgr/CMakeLists.txt
index 8e79bd0e..049449b7 100644
--- a/src/vpnsmgr/CMakeLists.txt
+++ b/src/vpnsmgr/CMakeLists.txt
@@ -5,9 +5,9 @@ endif()
 set(VPNSMGR_SOURCES vpnsmgr.c vpnsmgr.rc)
 
 if(${COMPILER_ARCHITECTURE} STREQUAL "x64")
-  set(VPNSMGR_SOURCES ${VPNSMGR_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x64_user.manifest)
+  set(VPNSMGR_SOURCES ${VPNSMGR_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x64_user.manifest)
 else()
-  set(VPNSMGR_SOURCES ${VPNSMGR_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x86_user.manifest)
+  set(VPNSMGR_SOURCES ${VPNSMGR_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x86_user.manifest)
 endif()
 
 add_executable(vpnsmgr WIN32 ${VPNSMGR_SOURCES})
diff --git a/src/vpntest/CMakeLists.txt b/src/vpntest/CMakeLists.txt
index 9e3dde20..b05f3892 100644
--- a/src/vpntest/CMakeLists.txt
+++ b/src/vpntest/CMakeLists.txt
@@ -2,9 +2,9 @@ set(VPNTEST_SOURCES vpntest.c vpntest.h)
 
 if(WIN32)
   if(${COMPILER_ARCHITECTURE} STREQUAL "x64")
-    set(VPNTEST_SOURCES ${VPNTEST_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x64_user.manifest)
+    set(VPNTEST_SOURCES ${VPNTEST_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x64_user.manifest)
   else()
-    set(VPNTEST_SOURCES ${VPNTEST_SOURCES} ${CMAKE_SOURCE_DIR}/src/BuildFiles/Manifests/x86_user.manifest)
+    set(VPNTEST_SOURCES ${VPNTEST_SOURCES} ${TOP_DIRECTORY}/src/BuildFiles/Manifests/x86_user.manifest)
   endif()
 endif()