diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index 8908fe230b0..fc0a9f69003 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -547,7 +547,7 @@ impl<'tcx> WfPredicates<'tcx> {
                 }
 
                 ty::FnDef(did, substs) => {
-                    let obligations = self.nominal_obligations(did, substs);
+                    let obligations = self.nominal_obligations_without_const(did, substs);
                     self.out.extend(obligations);
                 }
 
diff --git a/src/test/ui/consts/issue-104155.rs b/src/test/ui/consts/issue-104155.rs
new file mode 100644
index 00000000000..1cc8f81b0d2
--- /dev/null
+++ b/src/test/ui/consts/issue-104155.rs
@@ -0,0 +1,5 @@
+// check-pass
+const _: () = core::mem::forget(Box::<u32>::default);
+const _: () = core::mem::forget(|| Box::<u32>::default());
+
+fn main() {}