diff --git a/lix/libexpr/eval.cc b/lix/libexpr/eval.cc
index 202273202..84ed1130a 100644
--- a/lix/libexpr/eval.cc
+++ b/lix/libexpr/eval.cc
@@ -108,6 +108,7 @@ std::string showType(const Value & v)
             case Value::Acb::tExternal:
                 return v.external()->showType();
             case Value::Acb::tFloat:
+            case Value::Acb::tNull:
                 return std::string(showType(v.type()));
             }
 #pragma GCC diagnostic pop
diff --git a/lix/libexpr/value.cc b/lix/libexpr/value.cc
index e8835808e..9c95a3c5d 100644
--- a/lix/libexpr/value.cc
+++ b/lix/libexpr/value.cc
@@ -12,6 +12,8 @@ namespace nix
 static const Value::List emptyListData{.size = 0};
 Value Value::EMPTY_LIST{Value::list_t{}, &emptyListData};
 
+const Value::Null Value::NULL_ACB = {{Value::Acb::tNull}};
+
 static void copyContextToValue(Value::String & s, const NixStringContext & context)
 {
     if (!context.empty()) {
diff --git a/lix/libexpr/value.hh b/lix/libexpr/value.hh
index 7bccb785b..50a9b7b11 100644
--- a/lix/libexpr/value.hh
+++ b/lix/libexpr/value.hh
@@ -26,7 +26,6 @@ typedef enum {
     tInt = 1,
     tBool,
     tString,
-    tNull,
     tAttrs,
     tList,
     tThunk,
@@ -214,6 +213,9 @@ public:
 
     struct String;
     struct Acb;
+    struct Null;
+
+    static const Null NULL_ACB;
 
     // Discount `using NewValueAs::*;`
 // NOLINTNEXTLINE(bugprone-macro-parentheses)
@@ -416,10 +418,7 @@ public:
     }
 
     /// Constructs a nix language value of the singleton type "null".
-    Value(null_t)
-        : internalType(tNull)
-        , _empty{0, 0}
-    { }
+    Value(null_t) : Value(NULL_ACB) {}
 
     /// Constructs a nix language value of type "set", with the attribute
     /// bindings pointed to by @ref bindings.
@@ -640,6 +639,7 @@ public:
         enum {
             tExternal,
             tFloat,
+            tNull,
         } type;
     };
     struct External : Acb
@@ -650,6 +650,8 @@ public:
     {
         NixFloat value;
     };
+    struct Null : Acb
+    {};
 
     union
     {
@@ -710,7 +712,6 @@ public:
             case tBool: return nBool;
             case tString:
                 return _string->isPath() ? nPath : nString;
-            case tNull: return nNull;
             case tAttrs: return nAttrs;
             case tList:
                 return nList;
@@ -723,6 +724,8 @@ public:
                     return nExternal;
                 case Acb::tFloat:
                     return nFloat;
+                case Acb::tNull:
+                    return nNull;
                 }
             case tThunk:
                 return nThunk;
@@ -790,8 +793,7 @@ public:
 
     inline void mkNull()
     {
-        clearValue();
-        internalType = tNull;
+        *this = {NewValueAs::null};
     }
 
     inline void mkAttrs(Bindings * a)