diff --git a/CMLibCommon.cmake b/CMLibCommon.cmake
index 53d088d..b8a00e0 100644
--- a/CMLibCommon.cmake
+++ b/CMLibCommon.cmake
@@ -13,7 +13,9 @@ include(CMLibDisableInSourceBuild)
 include(CMakeParseArguments)
 include(GNUInstallDirs)
 if(DEFINED ENV{DEB_HOST_MULTIARCH})
-  string(APPEND CMAKE_INSTALL_LIBDIR "/$ENV{DEB_HOST_MULTIARCH}")
+  if(NOT CMAKE_INSTALL_LIBDIR MATCHES $ENV{DEB_HOST_MULTIARCH})
+    string(APPEND CMAKE_INSTALL_LIBDIR "/$ENV{DEB_HOST_MULTIARCH}")
+  endif()
 endif()
 
 set(CMAKE_CXX_SOURCE_FILE_EXTENSIONS ${CMAKE_CXX_SOURCE_FILE_EXTENSIONS};tpp;tcc)