diff --git a/core/index.go b/core/index.go
index 9cbdc48..05b11eb 100644
--- a/core/index.go
+++ b/core/index.go
@@ -26,12 +26,13 @@ type Index struct {
 
 // IndexFile is a file in the index
 type IndexFile struct {
-	// Files are stored in relative forward-slash format to the index file
+	// Files are stored in forward-slash format relative to the index file
 	File           string `toml:"file"`
 	Hash           string `toml:"hash"`
 	HashFormat     string `toml:"hash-format,omitempty"`
 	Alias          string `toml:"alias,omitempty"`
 	MetaFile       bool   `toml:"metafile,omitempty"` // True when it is a .toml metadata file
+	Preserve       bool   `toml:"preserve,omitempty"` // Don't overwrite the file when updating
 	fileExistsTemp bool
 }
 
diff --git a/core/mod.go b/core/mod.go
index b69e9b2..6fdd801 100644
--- a/core/mod.go
+++ b/core/mod.go
@@ -16,11 +16,16 @@ type Mod struct {
 	Name     string      `toml:"name"`
 	FileName string      `toml:"filename"`
 	Side     string      `toml:"side,omitempty"`
-	Optional bool        `toml:"optional,omitempty"`
 	Download ModDownload `toml:"download"`
 	// Update is a map of map of stuff, so you can store arbitrary values on string keys to define updating
 	Update     map[string]map[string]interface{} `toml:"update"`
 	updateData map[string]interface{}
+
+	Option *struct {
+		Optional    bool   `toml:"optional"`
+		Description string `toml:"description,omitempty"`
+		Default     bool   `toml:"default,omitempty"`
+	} `toml:"option,omitempty"`
 }
 
 // ModDownload specifies how to download the mod file
@@ -95,4 +100,4 @@ func (m Mod) GetParsedUpdateData(updaterName string) (interface{}, bool) {
 // GetFilePath is a clumsy hack that I made because Mod already stores it's path anyway
 func (m Mod) GetFilePath() string {
 	return m.metaFile
-}
\ No newline at end of file
+}