diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 1841a06eb89..0995231c639 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -30,8 +30,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let kind = match e.kind {
                 ExprKind::Box(ref inner) => hir::ExprKind::Box(self.lower_expr(inner)),
                 ExprKind::Array(ref exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
-                ExprKind::ConstBlock(_) => {
-                    unimplemented!();
+                ExprKind::ConstBlock(ref anon_const) => {
+                    let anon_const = self.lower_anon_const(anon_const);
+                    hir::ExprKind::ConstBlock(anon_const)
                 }
                 ExprKind::Repeat(ref expr, ref count) => {
                     let expr = self.lower_expr(expr);
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index d9791fe743c..b1c8e0ee727 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -287,7 +287,7 @@ impl<'a> AstValidator<'a> {
     // ```
     fn check_expr_within_pat(&self, expr: &Expr, allow_paths: bool) {
         match expr.kind {
-            ExprKind::Lit(..) | ExprKind::Err => {}
+            ExprKind::Lit(..) | ExprKind::ConstBlock(..) | ExprKind::Err => {}
             ExprKind::Path(..) if allow_paths => {}
             ExprKind::Unary(UnOp::Neg, ref inner) if matches!(inner.kind, ExprKind::Lit(_)) => {}
             _ => self.err_handler().span_err(