diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 932e1d756..28a437e56 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -324,7 +324,9 @@ struct curlFileTransfer : public FileTransfer
             curl_easy_setopt(req, CURLOPT_MAXREDIRS, 10);
             curl_easy_setopt(req, CURLOPT_NOSIGNAL, 1);
             curl_easy_setopt(req, CURLOPT_USERAGENT,
-                ("curl/" LIBCURL_VERSION " Nix/" + nixVersion +
+                ("curl/" LIBCURL_VERSION
+                    " Nix/" + nixVersion +
+                    " DeterminateNix/" + determinateNixVersion +
                     (fileTransferSettings.userAgentSuffix != "" ? " " + fileTransferSettings.userAgentSuffix.get() : "")).c_str());
             #if LIBCURL_VERSION_NUM >= 0x072b00
             curl_easy_setopt(req, CURLOPT_PIPEWAIT, 1);