3 files changed, 9 insertions, 4 deletions
diff --git a/src/libutil/abstract-setting-to-json.hh b/src/libutil/abstract-setting-to-json.hh
index b3fbc84f7..2d82b54e7 100644
--- a/src/libutil/abstract-setting-to-json.hh
+++ b/src/libutil/abstract-setting-to-json.hh
@@ -10,6 +10,7 @@ std::map<std::string, nlohmann::json> BaseSetting<T>::toJSONObject()
     auto obj = AbstractSetting::toJSONObject();
     obj.emplace("value", value);
     obj.emplace("defaultValue", defaultValue);
+    obj.emplace("documentDefault", documentDefault);
     return obj;
 }
 }
diff --git a/src/libutil/config.hh b/src/libutil/config.hh
index 736810bf3..79ec0f9cf 100644
--- a/src/libutil/config.hh
+++ b/src/libutil/config.hh
@@ -232,16 +232,19 @@ protected:
 
     T value;
     const T defaultValue;
+    const bool documentDefault;
 
 public:
 
     BaseSetting(const T & def,
+        const bool documentDefault,
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
         : AbstractSetting(name, description, aliases)
         , value(def)
         , defaultValue(def)
+        , documentDefault(documentDefault)
     { }
 
     operator const T &() const { return value; }
@@ -288,8 +291,9 @@ public:
         const T & def,
         const std::string & name,
         const std::string & description,
-        const std::set<std::string> & aliases = {})
-        : BaseSetting<T>(def, name, description, aliases)
+        const std::set<std::string> & aliases = {},
+        const bool documentDefault = true)
+        : BaseSetting<T>(def, documentDefault, name, description, aliases)
     {
         options->addSetting(this);
     }
@@ -311,7 +315,7 @@ public:
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
-        : BaseSetting<Path>(def, name, description, aliases)
+        : BaseSetting<Path>(def, true, name, description, aliases)
         , allowEmpty(allowEmpty)
     {
         options->addSetting(this);
diff --git a/src/libutil/tests/config.cc b/src/libutil/tests/config.cc
index 0ebdaf3db..8be6730dd 100644
--- a/src/libutil/tests/config.cc
+++ b/src/libutil/tests/config.cc
@@ -161,7 +161,7 @@ namespace nix {
         Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
         setting.assign("value");
 
-        ASSERT_EQ(config.toJSON().dump(), R"#({"name-of-the-setting":{"aliases":[],"defaultValue":"","description":"description\n","value":"value"}})#");
+        ASSERT_EQ(config.toJSON().dump(), R"#({"name-of-the-setting":{"aliases":[],"defaultValue":"","description":"description\n","documentDefault":true,"value":"value"}})#");
     }
 
     TEST(Config, setSettingAlias) {