diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index 722def2563cbd..9d7deebac48e4 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -474,9 +474,9 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<Ty
             VariantData::Unit(..) | VariantData::Struct { .. } => {
                 tcx.type_of(tcx.hir().get_parent_item(hir_id)).instantiate_identity()
             }
-            VariantData::Tuple(..) => {
+            VariantData::Tuple(_, _, ctor) => {
                 let args = ty::GenericArgs::identity_for_item(tcx, def_id);
-                Ty::new_fn_def(tcx, def_id.to_def_id(), args)
+                Ty::new_fn_def(tcx, ctor.to_def_id(), args)
             }
         },
 
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index b5e619f1e2a3c..ba0898e07c295 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -11,7 +11,7 @@ use crate::ty::{
 };
 use crate::ty::{GenericArg, GenericArgs, GenericArgsRef};
 use crate::ty::{List, ParamEnv};
-use hir::def::DefKind;
+use hir::def::{CtorKind, DefKind};
 use rustc_data_structures::captures::Captures;
 use rustc_errors::{DiagArgValue, ErrorGuaranteed, IntoDiagArg, MultiSpan};
 use rustc_hir as hir;
@@ -1677,6 +1677,10 @@ impl<'tcx> Ty<'tcx> {
         def_id: DefId,
         args: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> Ty<'tcx> {
+        debug_assert_matches!(
+            tcx.def_kind(def_id),
+            DefKind::AssocFn | DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn)
+        );
         let args = tcx.check_and_mk_args(def_id, args);
         Ty::new(tcx, FnDef(def_id, args))
     }