diff --git a/internal/lsp/cache/snapshot.go b/internal/lsp/cache/snapshot.go
index d8b2462..019a7e6 100644
--- a/internal/lsp/cache/snapshot.go
+++ b/internal/lsp/cache/snapshot.go
@@ -326,6 +326,8 @@
 			inv.ModFlag = "vendor"
 		} else if !allowModfileModificationOption {
 			inv.ModFlag = "readonly"
+		} else {
+			inv.ModFlag = mutableModFlag
 		}
 	case source.UpdateUserModFile, source.WriteTemporaryModFile:
 		inv.ModFlag = mutableModFlag