diff --git a/boot-v1.go b/boot-v1.go
index f439d18..da33a20 100644
--- a/boot-v1.go
+++ b/boot-v1.go
@@ -147,7 +147,12 @@ func applyConfig(cfgPath string, bootMounted bool) (cfg *configV1) {
 			log.Printf("failed to create dir %s: %v", filepath.Dir(fileDef.Path), err)
 		}
 
-		err = os.WriteFile(filePath, []byte(fileDef.Content), fileDef.Mode)
+		mode := fileDef.Mode
+		if mode == 0 {
+			mode = 0644
+		}
+
+		err = os.WriteFile(filePath, []byte(fileDef.Content), mode)
 		if err != nil {
 			fatalf("failed to write %s: %v", fileDef.Path, err)
 		}