diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index f01f12860..8170bd579 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -484,7 +484,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
                 auto path = state->coerceToPath(noPos, v, context, "while evaluating the filename to edit");
                 return {path, 0};
             } else if (v.isLambda()) {
-                auto pos = state->positions[v.payload.lambda.fun->pos];
+                auto pos = state->positions[v.lambda().fun->pos];
                 if (auto path = std::get_if<SourcePath>(&pos.origin))
                     return {*path, pos.line};
                 else
diff --git a/src/libexpr-tests/primops.cc b/src/libexpr-tests/primops.cc
index 2f864f2c2..6c301f157 100644
--- a/src/libexpr-tests/primops.cc
+++ b/src/libexpr-tests/primops.cc
@@ -667,8 +667,8 @@ namespace nix {
         auto v = eval("derivation");
         ASSERT_EQ(v.type(), nFunction);
         ASSERT_TRUE(v.isLambda());
-        ASSERT_NE(v.payload.lambda.fun, nullptr);
-        ASSERT_TRUE(v.payload.lambda.fun->hasFormals());
+        ASSERT_NE(v.lambda().fun, nullptr);
+        ASSERT_TRUE(v.lambda().fun->hasFormals());
     }
 
     TEST_F(PrimOpTest, currentTime) {
diff --git a/src/libexpr/eval-profiler.cc b/src/libexpr/eval-profiler.cc
index 7053e4ec7..b65bc3a4d 100644
--- a/src/libexpr/eval-profiler.cc
+++ b/src/libexpr/eval-profiler.cc
@@ -204,7 +204,7 @@ FrameInfo SampleStack::getFrameInfoFromValueAndPos(const Value & v, std::span<Va
     /* NOTE: No actual references to garbage collected values are not held in
        the profiler. */
     if (v.isLambda())
-        return LambdaFrameInfo{.expr = v.payload.lambda.fun, .callPos = pos};
+        return LambdaFrameInfo{.expr = v.lambda().fun, .callPos = pos};
     else if (v.isPrimOp()) {
         return getPrimOpFrameInfo(*v.primOp(), args, pos);
     } else if (v.isPrimOpApp())
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 7346a7651..51036a223 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -147,7 +147,7 @@ PosIdx Value::determinePos(const PosIdx pos) const
     #pragma GCC diagnostic ignored "-Wswitch-enum"
     switch (internalType) {
         case tAttrs: return attrs()->pos;
-        case tLambda: return payload.lambda.fun->pos;
+        case tLambda: return lambda().fun->pos;
         case tApp: return payload.app.left->determinePos(pos);
         default: return pos;
     }
@@ -610,7 +610,7 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
             };
     }
     if (v.isLambda()) {
-        auto exprLambda = v.payload.lambda.fun;
+        auto exprLambda = v.lambda().fun;
 
         std::ostringstream s;
         std::string name;
@@ -1567,13 +1567,13 @@ void EvalState::callFunction(Value & fun, std::span<Value *> args, Value & vRes,
 
         if (vCur.isLambda()) {
 
-            ExprLambda & lambda(*vCur.payload.lambda.fun);
+            ExprLambda & lambda(*vCur.lambda().fun);
 
             auto size =
                 (!lambda.arg ? 0 : 1) +
                 (lambda.hasFormals() ? lambda.formals->formals.size() : 0);
             Env & env2(allocEnv(size));
-            env2.up = vCur.payload.lambda.env;
+            env2.up = vCur.lambda().env;
 
             Displacement displ = 0;
 
@@ -1603,7 +1603,7 @@ void EvalState::callFunction(Value & fun, std::span<Value *> args, Value & vRes,
                                              symbols[i.name])
                                     .atPos(lambda.pos)
                                     .withTrace(pos, "from call site")
-                                    .withFrame(*fun.payload.lambda.env, lambda)
+                                    .withFrame(*fun.lambda().env, lambda)
                                     .debugThrow();
                         }
                         env2.values[displ++] = i.def->maybeThunk(*this, env2);
@@ -1630,7 +1630,7 @@ void EvalState::callFunction(Value & fun, std::span<Value *> args, Value & vRes,
                                 .atPos(lambda.pos)
                                 .withTrace(pos, "from call site")
                                 .withSuggestions(suggestions)
-                                .withFrame(*fun.payload.lambda.env, lambda)
+                                .withFrame(*fun.lambda().env, lambda)
                                 .debugThrow();
                         }
                     unreachable();
@@ -1825,14 +1825,14 @@ void EvalState::autoCallFunction(const Bindings & args, Value & fun, Value & res
         }
     }
 
-    if (!fun.isLambda() || !fun.payload.lambda.fun->hasFormals()) {
+    if (!fun.isLambda() || !fun.lambda().fun->hasFormals()) {
         res = fun;
         return;
     }
 
-    auto attrs = buildBindings(std::max(static_cast<uint32_t>(fun.payload.lambda.fun->formals->formals.size()), args.size()));
+    auto attrs = buildBindings(std::max(static_cast<uint32_t>(fun.lambda().fun->formals->formals.size()), args.size()));
 
-    if (fun.payload.lambda.fun->formals->ellipsis) {
+    if (fun.lambda().fun->formals->ellipsis) {
         // If the formals have an ellipsis (eg the function accepts extra args) pass
         // all available automatic arguments (which includes arguments specified on
         // the command line via --arg/--argstr)
@@ -1840,7 +1840,7 @@ void EvalState::autoCallFunction(const Bindings & args, Value & fun, Value & res
             attrs.insert(v);
     } else {
         // Otherwise, only pass the arguments that the function accepts
-        for (auto & i : fun.payload.lambda.fun->formals->formals) {
+        for (auto & i : fun.lambda().fun->formals->formals) {
             auto j = args.get(i.name);
             if (j) {
                 attrs.insert(*j);
@@ -1850,7 +1850,7 @@ Nix attempted to evaluate a function as a top level expression; in
 this case it must have its arguments supplied either by default
 values, or passed explicitly with '--arg' or '--argstr'. See
 https://nixos.org/manual/nix/stable/language/constructs.html#functions.)", symbols[i.name])
-                    .atPos(i.pos).withFrame(*fun.payload.lambda.env, *fun.payload.lambda.fun).debugThrow();
+                    .atPos(i.pos).withFrame(*fun.lambda().env, *fun.lambda().fun).debugThrow();
             }
         }
     }
diff --git a/src/libexpr/include/nix/expr/value.hh b/src/libexpr/include/nix/expr/value.hh
index febe36f80..26ec5ff38 100644
--- a/src/libexpr/include/nix/expr/value.hh
+++ b/src/libexpr/include/nix/expr/value.hh
@@ -482,6 +482,9 @@ public:
 
     NixFloat fpoint() const
     { return payload.fpoint; }
+
+    Lambda lambda() const
+    { return payload.lambda; }
 };
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 48bc272f9..a24695bcd 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3138,12 +3138,12 @@ static void prim_functionArgs(EvalState & state, const PosIdx pos, Value * * arg
     if (!args[0]->isLambda())
         state.error<TypeError>("'functionArgs' requires a function").atPos(pos).debugThrow();
 
-    if (!args[0]->payload.lambda.fun->hasFormals()) {
+    if (!args[0]->lambda().fun->hasFormals()) {
         v.mkAttrs(&state.emptyBindings);
         return;
     }
 
-    const auto &formals = args[0]->payload.lambda.fun->formals->formals;
+    const auto &formals = args[0]->lambda().fun->formals->formals;
     auto attrs = state.buildBindings(formals.size());
     for (auto & i : formals)
         attrs.insert(i.name, state.getBool(i.def), i.pos);
diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc
index 06bae9c5c..f0e0eed2d 100644
--- a/src/libexpr/print.cc
+++ b/src/libexpr/print.cc
@@ -453,13 +453,13 @@ private:
 
         if (v.isLambda()) {
             output << "lambda";
-            if (v.payload.lambda.fun) {
-                if (v.payload.lambda.fun->name) {
-                    output << " " << state.symbols[v.payload.lambda.fun->name];
+            if (v.lambda().fun) {
+                if (v.lambda().fun->name) {
+                    output << " " << state.symbols[v.lambda().fun->name];
                 }
 
                 std::ostringstream s;
-                s << state.positions[v.payload.lambda.fun->pos];
+                s << state.positions[v.lambda().fun->pos];
                 output << " @ " << filterANSIEscapes(toView(s));
             }
         } else if (v.isPrimOp()) {
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index e26fff71b..54ff06f9e 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -126,18 +126,18 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
                 break;
             }
             XMLAttrs xmlAttrs;
-            if (location) posToXML(state, xmlAttrs, state.positions[v.payload.lambda.fun->pos]);
+            if (location) posToXML(state, xmlAttrs, state.positions[v.lambda().fun->pos]);
             XMLOpenElement _(doc, "function", xmlAttrs);
 
-            if (v.payload.lambda.fun->hasFormals()) {
+            if (v.lambda().fun->hasFormals()) {
                 XMLAttrs attrs;
-                if (v.payload.lambda.fun->arg) attrs["name"] = state.symbols[v.payload.lambda.fun->arg];
-                if (v.payload.lambda.fun->formals->ellipsis) attrs["ellipsis"] = "1";
+                if (v.lambda().fun->arg) attrs["name"] = state.symbols[v.lambda().fun->arg];
+                if (v.lambda().fun->formals->ellipsis) attrs["ellipsis"] = "1";
                 XMLOpenElement _(doc, "attrspat", attrs);
-                for (auto & i : v.payload.lambda.fun->formals->lexicographicOrder(state.symbols))
+                for (auto & i : v.lambda().fun->formals->lexicographicOrder(state.symbols))
                     doc.writeEmptyElement("attr", singletonAttrs("name", state.symbols[i.name]));
             } else
-                doc.writeEmptyElement("varpat", singletonAttrs("name", state.symbols[v.payload.lambda.fun->arg]));
+                doc.writeEmptyElement("varpat", singletonAttrs("name", state.symbols[v.lambda().fun->arg]));
 
             break;
         }
diff --git a/src/libflake/flake.cc b/src/libflake/flake.cc
index 24252d710..41141d41d 100644
--- a/src/libflake/flake.cc
+++ b/src/libflake/flake.cc
@@ -252,8 +252,8 @@ static Flake readFlake(
     if (auto outputs = vInfo.attrs()->get(sOutputs)) {
         expectType(state, nFunction, *outputs->value, outputs->pos);
 
-        if (outputs->value->isLambda() && outputs->value->payload.lambda.fun->hasFormals()) {
-            for (auto & formal : outputs->value->payload.lambda.fun->formals->formals) {
+        if (outputs->value->isLambda() && outputs->value->lambda().fun->hasFormals()) {
+            for (auto & formal : outputs->value->lambda().fun->formals->formals) {
                 if (formal.name != state.sSelf)
                     flake.inputs.emplace(state.symbols[formal.name], FlakeInput {
                         .ref = parseFlakeRef(state.fetchSettings, std::string(state.symbols[formal.name]))
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 80ebf6bfa..e302aca67 100644
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -387,8 +387,8 @@ static void main_nix_build(int argc, char * * argv)
                 return false;
             }
             bool add = false;
-            if (v.type() == nFunction && v.payload.lambda.fun->hasFormals()) {
-                for (auto & i : v.payload.lambda.fun->formals->formals) {
+            if (v.type() == nFunction && v.lambda().fun->hasFormals()) {
+                for (auto & i : v.lambda().fun->formals->formals) {
                     if (state->symbols[i.name] == "inNixShell") {
                         add = true;
                         break;
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 95cf85663..13f7363fc 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -492,8 +492,8 @@ struct CmdFlakeCheck : FlakeCommand
                 if (!v.isLambda()) {
                     throw Error("overlay is not a function, but %s instead", showType(v));
                 }
-                if (v.payload.lambda.fun->hasFormals()
-                    || !argHasName(v.payload.lambda.fun->arg, "final"))
+                if (v.lambda().fun->hasFormals()
+                    || !argHasName(v.lambda().fun->arg, "final"))
                     throw Error("overlay does not take an argument named 'final'");
                 // FIXME: if we have a 'nixpkgs' input, use it to
                 // evaluate the overlay.