diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index de74d2143..887b2946f 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -136,14 +136,14 @@ struct AttrDb
         });
     }
 
-    AttrId setString(AttrKey key, std::string_view s, const char ** context = nullptr)
+    AttrId setString(AttrKey key, std::string_view s, Value::StringWithContext::Context context = nullptr)
     {
         return doSQLite([&]() {
             auto state(_state->lock());
 
             if (context) {
                 std::string ctx;
-                for (const char ** p = context; *p; ++p) {
+                for (Value::StringWithContext::Context p = context; *p; ++p) {
                     if (p != context)
                         ctx.push_back(' ');
                     ctx.append(*p);
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index e2687148b..f25a72511 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -821,11 +821,11 @@ void Value::mkString(std::string_view s)
     mkStringNoCopy(makeImmutableString(s));
 }
 
-static const char ** encodeContext(const NixStringContext & context)
+static Value::StringWithContext::Context encodeContext(const NixStringContext & context)
 {
     if (!context.empty()) {
         size_t n = 0;
-        auto ctx = (const char **) allocBytes((context.size() + 1) * sizeof(char *));
+        auto ctx = (Value::StringWithContext::Context) allocBytes((context.size() + 1) * sizeof(char *));
         for (auto & i : context) {
             ctx[n++] = makeImmutableString({i.to_string()});
         }
@@ -2288,7 +2288,7 @@ std::string_view EvalState::forceString(Value & v, const PosIdx pos, std::string
 void copyContext(const Value & v, NixStringContext & context, const ExperimentalFeatureSettings & xpSettings)
 {
     if (v.context())
-        for (const char ** p = v.context(); *p; ++p)
+        for (Value::StringWithContext::Context p = v.context(); *p; ++p)
             context.insert(NixStringContextElem::parse(*p, xpSettings));
 }
 
diff --git a/src/libexpr/include/nix/expr/value.hh b/src/libexpr/include/nix/expr/value.hh
index 706a4fe3f..65204b642 100644
--- a/src/libexpr/include/nix/expr/value.hh
+++ b/src/libexpr/include/nix/expr/value.hh
@@ -220,7 +220,18 @@ struct ValueBase
     struct StringWithContext
     {
         const char * c_str;
-        const char ** context; // must be in sorted order
+        /**
+         * The type of the context itself.
+         *
+         * Currently, it is pointer to an array of pointers to strings.
+         * The strings are specially formatted to represent a flattening
+         * of the recursive sum type that is s context element.
+         *
+         * @See NixStringContext for an more easily understood type,
+         * that of the "builder" for this data structure.
+         */
+        using Context = const char **;
+        Context context; // must be in sorted order
     };
 
     struct Path
@@ -991,7 +1002,7 @@ public:
         setStorage(b);
     }
 
-    void mkStringNoCopy(const char * s, const char ** context = 0) noexcept
+    void mkStringNoCopy(const char * s, Value::StringWithContext::Context context = 0) noexcept
     {
         setStorage(StringWithContext{.c_str = s, .context = context});
     }
@@ -1117,7 +1128,7 @@ public:
         return getStorage<StringWithContext>().c_str;
     }
 
-    const char ** context() const noexcept
+    Value::StringWithContext::Context context() const noexcept
     {
         return getStorage<StringWithContext>().context;
     }
diff --git a/src/libexpr/include/nix/expr/value/context.hh b/src/libexpr/include/nix/expr/value/context.hh
index dcfacbb21..625adc37b 100644
--- a/src/libexpr/include/nix/expr/value/context.hh
+++ b/src/libexpr/include/nix/expr/value/context.hh
@@ -24,6 +24,14 @@ public:
     }
 };
 
+/**
+ * @todo This should be reamed to `StringContextBuilderElem`, since:
+ *
+ * 1. We use `*Builder` for off-heap temporary data structures
+ *
+ * 2. The `Nix*` is totally redundant. (And my mistake from a long time
+ * ago.)
+ */
 struct NixStringContextElem
 {
     /**
@@ -77,6 +85,11 @@ struct NixStringContextElem
     std::string to_string() const;
 };
 
+/**
+ * @todo This should be renamed to `StringContextBuilder`.
+ *
+ * @see NixStringContextElem for explanation why.
+ */
 typedef std::set<NixStringContextElem> NixStringContext;
 
 } // namespace nix