diff --git a/src/libexpr/common-eval-args.hh b/src/libexpr/common-eval-args.hh
index 09fa406b2..be7fda783 100644
--- a/src/libexpr/common-eval-args.hh
+++ b/src/libexpr/common-eval-args.hh
@@ -6,7 +6,7 @@ namespace nix {
 
 class Store;
 class EvalState;
-struct Bindings;
+class Bindings;
 
 struct MixEvalArgs : virtual Args
 {
diff --git a/src/libexpr/primops/fetchgit.cc b/src/libexpr/primops/fetchgit.cc
index 879e3656a..4b5ead320 100644
--- a/src/libexpr/primops/fetchgit.cc
+++ b/src/libexpr/primops/fetchgit.cc
@@ -56,7 +56,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
         }
     }
 
-    if (!ref) ref = "master";
+    if (!ref) ref = "master"s;
 
     if (rev != "") {
         std::regex revRegex("^[0-9a-fA-F]{40}$");