diff --git a/src/libfetchers/cache.hh b/src/libfetchers/cache.hh
index d76ab1233..3db4f081c 100644
--- a/src/libfetchers/cache.hh
+++ b/src/libfetchers/cache.hh
@@ -6,6 +6,8 @@ namespace nix::fetchers {
 
 struct Cache
 {
+    virtual ~Cache() { }
+
     virtual void add(
         ref<Store> store,
         const Attrs & inAttrs,