diff --git a/src/libfetchers/cache.cc b/src/libfetchers/cache.cc
index 58c2142e5..2f0f7c719 100644
--- a/src/libfetchers/cache.cc
+++ b/src/libfetchers/cache.cc
@@ -25,6 +25,9 @@ create table if not exists Facts (
 );
 )sql";
 
+// FIXME: we should periodically purge/nuke this cache to prevent it
+// from growing too big.
+
 struct CacheImpl : Cache
 {
     struct State