diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 844553ad3..a7a9cd702 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -214,6 +214,14 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
     Stats stats;
 
     S3Helper s3Helper;
+    ref<Store> mNixosCache;
+
+    BinaryCacheStore * nixosCache() {
+        auto * casted = dynamic_cast<BinaryCacheStore *>(&*this->mNixosCache);
+        if (!casted)
+            throw UsageError("cache.nixos.org is not a BinaryCacheStore");
+        return casted;
+    }
 
     S3BinaryCacheStoreImpl(
         const std::string & uriScheme,
@@ -227,6 +235,7 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
         , S3BinaryCacheStore(params)
         , bucketName(bucketName)
         , s3Helper(profile, region, scheme, endpoint)
+        , mNixosCache(openStore("https://cache.nixos.org/"))
     {
         diskCache = getNarInfoDiskCache();
     }
@@ -268,6 +277,8 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
 
     bool fileExists(const std::string & path) override
     {
+        if(this->nixosCache()->fileExists(path))
+            return true;
         stats.head++;
 
         auto res = s3Helper.client->HeadObject(
@@ -389,6 +400,8 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
         std::shared_ptr<std::basic_iostream<char>> istream,
         const std::string & mimeType) override
     {
+        if(this->nixosCache()->fileExists(path))
+            return;
         auto compress = [&](std::string compression)
         {
             auto compressed = nix::compress(compression, StreamToSourceAdapter(istream).drain());
@@ -407,6 +420,8 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
 
     void getFile(const std::string & path, Sink & sink) override
     {
+        if(this->nixosCache()->fileExists(path))
+            return this->nixosCache()->getFile(path, sink);
         stats.get++;
 
         // FIXME: stream output to sink.