diff --git a/hyphae/categories/categories.go b/hyphae/categories/categories.go
index d46cc93..4ac180f 100644
--- a/hyphae/categories/categories.go
+++ b/hyphae/categories/categories.go
@@ -55,6 +55,7 @@ func AddHyphaToCategory(hyphaName, catName string) {
 		categoryToHyphae[catName] = &categoryNode{hyphaList: []string{hyphaName}}
 	}
 	mutex.Unlock()
+	go saveToDisk()
 }
 
 // RemoveHyphaFromCategory removes the hypha from the category and updates the records on the disk. If the hypha is not in the category, nothing happens.
@@ -68,4 +69,5 @@ func RemoveHyphaFromCategory(hyphaName, catName string) {
 		node.removeHypha(hyphaName)
 	}
 	mutex.Unlock()
+	go saveToDisk()
 }
diff --git a/hyphae/categories/files.go b/hyphae/categories/files.go
index 0cf17a7..fd5c3df 100644
--- a/hyphae/categories/files.go
+++ b/hyphae/categories/files.go
@@ -6,6 +6,7 @@ import (
 	"github.com/bouncepaw/mycorrhiza/util"
 	"log"
 	"os"
+	"sync"
 )
 
 var categoryToHyphae = map[string]*categoryNode{}
@@ -119,3 +120,28 @@ func readCategoriesFromDisk() (catFileRecord, error) {
 
 	return record, nil
 }
+
+var fileMutex sync.Mutex
+
+func saveToDisk() {
+	var (
+		record catFileRecord
+	)
+	for name, node := range categoryToHyphae {
+		record.Categories = append(record.Categories, catRecord{
+			Name:   name,
+			Hyphae: node.hyphaList,
+		})
+	}
+	data, err := json.MarshalIndent(record, "", "\t")
+	if err != nil {
+		log.Fatalln(err) // Better fail now, than later
+	}
+	// TODO: make the data safer somehow?? Back it up before overwriting?
+	fileMutex.Lock()
+	err = os.WriteFile(files.CategoriesJSON(), data, 0666)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	fileMutex.Unlock()
+}