diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc
index 71ab1edbf..19ef6f8aa 100644
--- a/src/libexpr/print.cc
+++ b/src/libexpr/print.cc
@@ -1,4 +1,5 @@
 #include <limits>
+#include <span>
 #include <unordered_set>
 
 #include "print.hh"
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 481cb76e8..5e0795115 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -13,6 +13,7 @@
 #include "topo-sort.hh"
 #include "callback.hh"
 #include "local-store.hh" // TODO remove, along with remaining downcasts
+#include "logging-json.hh"
 
 #include <regex>
 #include <queue>
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index ab84255d3..fef680421 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -8,6 +8,7 @@
 #include "common-protocol.hh"
 #include "common-protocol-impl.hh"
 #include "fs-accessor.hh"
+#include "json-utils.hh"
 #include <boost/container/small_vector.hpp>
 #include <nlohmann/json.hpp>
 
diff --git a/src/libutil/abstract-setting-to-json.hh b/src/libutil/abstract-setting-to-json.hh
index eea687d8a..60807412a 100644
--- a/src/libutil/abstract-setting-to-json.hh
+++ b/src/libutil/abstract-setting-to-json.hh
@@ -4,6 +4,8 @@
 #include <nlohmann/json.hpp>
 #include "config.hh"
 #include "json-utils.hh"
+// Required for instances of to_json and from_json for ExperimentalFeature
+#include "experimental-features-json.hh"
 
 namespace nix {
 template<typename T>
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index 3e39b4d7c..520f50c30 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -2,6 +2,7 @@
 #include "args/root.hh"
 #include "hash.hh"
 #include "json-utils.hh"
+#include "experimental-features-json.hh"
 
 #include <glob.h>
 
diff --git a/src/libutil/experimental-features-json.hh b/src/libutil/experimental-features-json.hh
new file mode 100644
index 000000000..a4f999a93
--- /dev/null
+++ b/src/libutil/experimental-features-json.hh
@@ -0,0 +1,29 @@
+#pragma once
+///@file
+
+#include "experimental-features.hh"
+#include "json-utils.hh"
+
+namespace nix {
+
+/**
+ * Compute the documentation of all experimental features.
+ *
+ * See `doc/manual` for how this information is used.
+ */
+nlohmann::json documentExperimentalFeatures();
+
+/**
+ * Semi-magic conversion to and from json.
+ * See the nlohmann/json readme for more details.
+ */
+void to_json(nlohmann::json &, const ExperimentalFeature &);
+void from_json(const nlohmann::json &, ExperimentalFeature &);
+
+/**
+ * It is always rendered as a string
+ */
+template<>
+struct json_avoids_null<ExperimentalFeature> : std::true_type {};
+
+};
diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
index d1e1d7423..25beba467 100644
--- a/src/libutil/experimental-features.cc
+++ b/src/libutil/experimental-features.cc
@@ -1,4 +1,6 @@
 #include "experimental-features.hh"
+// Required for instances of to_json and from_json for ExperimentalFeature
+#include "experimental-features-json.hh"
 #include "util.hh"
 
 #include "nlohmann/json.hpp"
diff --git a/src/libutil/experimental-features.hh b/src/libutil/experimental-features.hh
index cc841c0a6..38889e7bc 100644
--- a/src/libutil/experimental-features.hh
+++ b/src/libutil/experimental-features.hh
@@ -1,9 +1,7 @@
 #pragma once
 ///@file
 
-#include "comparator.hh"
 #include "error.hh"
-#include "json-utils.hh"
 #include "types.hh"
 
 namespace nix {
@@ -52,13 +50,6 @@ const std::optional<ExperimentalFeature> parseExperimentalFeature(
  */
 std::string_view showExperimentalFeature(const ExperimentalFeature);
 
-/**
- * Compute the documentation of all experimental features.
- *
- * See `doc/manual` for how this information is used.
- */
-nlohmann::json documentExperimentalFeatures();
-
 /**
  * Shorthand for `str << showExperimentalFeature(feature)`.
  */
@@ -87,17 +78,4 @@ public:
     MissingExperimentalFeature(ExperimentalFeature missingFeature);
 };
 
-/**
- * Semi-magic conversion to and from json.
- * See the nlohmann/json readme for more details.
- */
-void to_json(nlohmann::json &, const ExperimentalFeature &);
-void from_json(const nlohmann::json &, ExperimentalFeature &);
-
-/**
- * It is always rendered as a string
- */
-template<>
-struct json_avoids_null<ExperimentalFeature> : std::true_type {};
-
 }
diff --git a/src/libutil/logging-json.hh b/src/libutil/logging-json.hh
new file mode 100644
index 000000000..8263ad707
--- /dev/null
+++ b/src/libutil/logging-json.hh
@@ -0,0 +1,23 @@
+#pragma once
+///@file logging-json.hh
+///
+///@brief Logging functions for json specifically, split due to the cost of
+///including nlohmann.
+
+#include "logging.hh"
+
+#include <nlohmann/json_fwd.hpp>
+
+namespace nix {
+
+std::optional<nlohmann::json> parseJSONMessage(const std::string & msg);
+
+bool handleJSONLogMessage(nlohmann::json & json,
+    const Activity & act, std::map<ActivityId, Activity> & activities,
+    bool trusted);
+
+bool handleJSONLogMessage(const std::string & msg,
+    const Activity & act, std::map<ActivityId, Activity> & activities,
+    bool trusted);
+
+};
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index 7a6341d70..dc6f53d77 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -5,8 +5,6 @@
 #include "error.hh"
 #include "config.hh"
 
-#include <nlohmann/json_fwd.hpp>
-
 namespace nix {
 
 typedef enum {
@@ -184,16 +182,6 @@ Logger * makeSimpleLogger(bool printBuildLogs = true);
 
 Logger * makeJSONLogger(Logger & prevLogger);
 
-std::optional<nlohmann::json> parseJSONMessage(const std::string & msg);
-
-bool handleJSONLogMessage(nlohmann::json & json,
-    const Activity & act, std::map<ActivityId, Activity> & activities,
-    bool trusted);
-
-bool handleJSONLogMessage(const std::string & msg,
-    const Activity & act, std::map<ActivityId, Activity> & activities,
-    bool trusted);
-
 /**
  * suppress msgs > this
  */
diff --git a/src/libutil/meson.build b/src/libutil/meson.build
index 084d7ed11..66eba9d85 100644
--- a/src/libutil/meson.build
+++ b/src/libutil/meson.build
@@ -50,6 +50,7 @@ libutil_headers = files(
   'error.hh',
   'exit.hh',
   'experimental-features.hh',
+  'experimental-features-json.hh',
   'finally.hh',
   'fmt.hh',
   'git.hh',
@@ -59,6 +60,7 @@ libutil_headers = files(
   'json-impls.hh',
   'json-utils.hh',
   'logging.hh',
+  'logging-json.hh',
   'lru-cache.hh',
   'monitor-fd.hh',
   'namespaces.hh',
diff --git a/src/nix/main.cc b/src/nix/main.cc
index e033a5f5a..6bc46eba3 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -13,6 +13,7 @@
 #include "finally.hh"
 #include "loggers.hh"
 #include "markdown.hh"
+#include "experimental-features-json.hh"
 
 #include <sys/types.h>
 #include <sys/socket.h>
diff --git a/tests/unit/libutil-support/tests/cli-literate-parser.cc b/tests/unit/libutil-support/tests/cli-literate-parser.cc
index c943a813e..b3830e32c 100644
--- a/tests/unit/libutil-support/tests/cli-literate-parser.cc
+++ b/tests/unit/libutil-support/tests/cli-literate-parser.cc
@@ -3,6 +3,7 @@
 #include "debug-char.hh"
 #include "types.hh"
 #include "util.hh"
+#include <ranges>
 #include <iostream>
 #include <memory>
 #include <boost/algorithm/string/trim.hpp>