diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 40711a36c3..94bb8e1295 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -9435,7 +9435,8 @@ void cmGeneratorTarget::BuildFileSetInfoCache(std::string const& config) const
 
     for (auto const& it : files) {
       for (auto const& filename : it.second) {
-        per_config.FileSetCache[filename] = file_set;
+        auto collapsedFile = cmSystemTools::CollapseFullPath(filename);
+        per_config.FileSetCache[collapsedFile] = file_set;
       }
     }
   }