diff --git a/src/NexusMods.Paths/FileSystemAbstraction/InMemoryFileSystem/InMemoryFileSystem.cs b/src/NexusMods.Paths/FileSystemAbstraction/InMemoryFileSystem/InMemoryFileSystem.cs
index 4ba9829..8b38968 100644
--- a/src/NexusMods.Paths/FileSystemAbstraction/InMemoryFileSystem/InMemoryFileSystem.cs
+++ b/src/NexusMods.Paths/FileSystemAbstraction/InMemoryFileSystem/InMemoryFileSystem.cs
@@ -84,6 +84,8 @@ private InMemoryFileEntry InternalAddFile(AbsolutePath path, byte[] contents)
         _files.Add(path, inMemoryFile);
         directory.Files.Add(inMemoryFile.Path.RelativeTo(directory.Path), inMemoryFile);
 
+        inMemoryFile.CreationTime = DateTime.UtcNow;
+        inMemoryFile.LastWriteTime = DateTime.UtcNow;
         return inMemoryFile;
     }
 
@@ -288,6 +290,7 @@ private InMemoryFileEntry InternalCreateFile(AbsolutePath path, FileMode mode, F
         if (inMemoryFileEntry is null)
             throw new FileNotFoundException($"File \"{path.GetFullPath()}\" does not exist");
 
+        inMemoryFileEntry.LastWriteTime = DateTime.UtcNow;
         return inMemoryFileEntry;
     }