3 files changed, 12 insertions, 6 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 21b641f2c..8e795e555 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2521,7 +2521,7 @@ static std::regex shVarName("[A-Za-z_][A-Za-z0-9_]*");
 
 void DerivationGoal::writeStructuredAttrs()
 {
-    auto & structuredAttrs = parsedDrv->getStructuredAttrs();
+    auto structuredAttrs = parsedDrv->getStructuredAttrs();
     if (!structuredAttrs) return;
 
     auto json = *structuredAttrs;
diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index 87be8a24e..5553dd863 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -1,5 +1,7 @@
 #include "parsed-derivations.hh"
 
+#include <nlohmann/json.hpp>
+
 namespace nix {
 
 ParsedDerivation::ParsedDerivation(const Path & drvPath, BasicDerivation & drv)
@@ -9,13 +11,15 @@ ParsedDerivation::ParsedDerivation(const Path & drvPath, BasicDerivation & drv)
     auto jsonAttr = drv.env.find("__json");
     if (jsonAttr != drv.env.end()) {
         try {
-            structuredAttrs = nlohmann::json::parse(jsonAttr->second);
+            structuredAttrs = std::make_unique<nlohmann::json>(nlohmann::json::parse(jsonAttr->second));
         } catch (std::exception & e) {
             throw Error("cannot process __json attribute of '%s': %s", drvPath, e.what());
         }
     }
 }
 
+ParsedDerivation::~ParsedDerivation() { }
+
 std::optional<std::string> ParsedDerivation::getStringAttr(const std::string & name) const
 {
     if (structuredAttrs) {
diff --git a/src/libstore/parsed-derivations.hh b/src/libstore/parsed-derivations.hh
index 9bde4b4dc..6e67e1665 100644
--- a/src/libstore/parsed-derivations.hh
+++ b/src/libstore/parsed-derivations.hh
@@ -1,6 +1,6 @@
 #include "derivations.hh"
 
-#include <nlohmann/json.hpp>
+#include <nlohmann/json_fwd.hpp>
 
 namespace nix {
 
@@ -8,15 +8,17 @@ class ParsedDerivation
 {
     Path drvPath;
     BasicDerivation & drv;
-    std::optional<nlohmann::json> structuredAttrs;
+    std::unique_ptr<nlohmann::json> structuredAttrs;
 
 public:
 
     ParsedDerivation(const Path & drvPath, BasicDerivation & drv);
 
-    const std::optional<nlohmann::json> & getStructuredAttrs() const
+    ~ParsedDerivation();
+
+    const nlohmann::json * getStructuredAttrs() const
     {
-        return structuredAttrs;
+        return structuredAttrs.get();
     }
 
     std::optional<std::string> getStringAttr(const std::string & name) const;