diff --git a/Source/CPack/cmCPackPackageMakerGenerator.cxx b/Source/CPack/cmCPackPackageMakerGenerator.cxx
index d736948a2..e799d0615 100644
--- a/Source/CPack/cmCPackPackageMakerGenerator.cxx
+++ b/Source/CPack/cmCPackPackageMakerGenerator.cxx
@@ -964,6 +964,7 @@ cmCPackPackageMakerGenerator::CreateChoice(const cmCPackComponent& component,
   std::string dirName = this->GetOption("CPACK_TEMPORARY_DIRECTORY");
   dirName += '/';
   dirName += component.Name;
+  dirName += this->GetOption("CPACK_PACKAGING_INSTALL_PREFIX");
   unsigned long installedSize
     = component.GetInstalledSizeInKbytes(dirName.c_str());