diff --git a/third_party/nix/src/libexpr/get-drvs.hh b/third_party/nix/src/libexpr/get-drvs.hh
index bb20c32c0..30645123e 100644
--- a/third_party/nix/src/libexpr/get-drvs.hh
+++ b/third_party/nix/src/libexpr/get-drvs.hh
@@ -7,7 +7,7 @@
 
 namespace nix {
 
-struct DrvInfo {
+struct DrvInfo : public gc {
  public:
   typedef std::map<std::string, Path> Outputs;
 
diff --git a/third_party/nix/src/nix-env/nix-env.cc b/third_party/nix/src/nix-env/nix-env.cc
index 07bcb54eb..820b8cbca 100644
--- a/third_party/nix/src/nix-env/nix-env.cc
+++ b/third_party/nix/src/nix-env/nix-env.cc
@@ -48,7 +48,7 @@ struct InstallSourceInfo {
   Bindings* autoArgs;
 };
 
-struct Globals {
+struct Globals : public gc {
   InstallSourceInfo instSource;
   Path profile;
   std::shared_ptr<EvalState> state;