diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/CacheRepository.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/CacheRepository.java
index 1a4497d72..d8011ee2f 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/CacheRepository.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/CacheRepository.java
@@ -72,6 +72,7 @@ public class CacheRepository {
                 }
             } else {
                 index = new LinkedHashMap<>();
+                indexFileLastModified = null;
             }
         } catch (IOException | JsonParseException e) {
             LOG.warning("Unable to read index file", e);