diff --git a/nixd/lib/Sema/Lowering.cpp b/nixd/lib/Sema/Lowering.cpp
index ae37271bb..eacc0bf0d 100644
--- a/nixd/lib/Sema/Lowering.cpp
+++ b/nixd/lib/Sema/Lowering.cpp
@@ -2,6 +2,7 @@
 #include "nixd/Sema/EvalContext.h"
 #include "nixd/Syntax/Diagnostic.h"
 #include "nixd/Syntax/Nodes.h"
+#include "nixexpr.hh"
 
 namespace nixd {
 
@@ -122,6 +123,22 @@ nix::Expr *Lowering::lower(EvalContext &Ctx, nixd::syntax::Node *Root) {
     auto *Fn = dynamic_cast<syntax::Function *>(Root);
     return lowerFunction(Ctx, Fn);
   }
+  case Node::NK_Assert: {
+    auto *Assert = dynamic_cast<syntax::Assert *>(Root);
+    auto *Cond = lower(Ctx, Assert->Cond);
+    auto *Body = lower(Ctx, Assert->Body);
+    auto *NixAssert =
+        Ctx.Pool.record(new nix::ExprAssert(Assert->Range.Begin, Cond, Body));
+    return NixAssert;
+  }
+  case Node::NK_With: {
+    auto *With = dynamic_cast<syntax::With *>(Root);
+    auto *Attrs = lower(Ctx, With->Attrs);
+    auto *Body = lower(Ctx, With->Body);
+    auto *NixWith =
+        Ctx.Pool.record(new nix::ExprWith(With->Range.Begin, Attrs, Body));
+    return NixWith;
+  }
   }
 
   return nullptr;
diff --git a/nixd/tools/nixd-lint/test/lowering-assert.nix b/nixd/tools/nixd-lint/test/lowering-assert.nix
new file mode 100644
index 000000000..5ea4d7a73
--- /dev/null
+++ b/nixd/tools/nixd-lint/test/lowering-assert.nix
@@ -0,0 +1,4 @@
+# RUN: nixd-lint %s | FileCheck %s
+
+# CHECK: function argument duplicated to a function formal
+assert 0; a @ { a }: 1
diff --git a/nixd/tools/nixd-lint/test/lowering-with.nix b/nixd/tools/nixd-lint/test/lowering-with.nix
new file mode 100644
index 000000000..94418a533
--- /dev/null
+++ b/nixd/tools/nixd-lint/test/lowering-with.nix
@@ -0,0 +1,4 @@
+# RUN: nixd-lint %s | FileCheck %s
+
+# CHECK: function argument duplicated to a function formal
+with 1; { a } @ a : 1