diff --git a/gcc/rust/checks/errors/rust-const-checker.cc b/gcc/rust/checks/errors/rust-const-checker.cc
index 43618345a538..50f56af2d854 100644
--- a/gcc/rust/checks/errors/rust-const-checker.cc
+++ b/gcc/rust/checks/errors/rust-const-checker.cc
@@ -861,7 +861,7 @@ void
 ConstChecker::visit (ReferenceType &type)
 {
   if (const_context.is_in_context () && type.is_mut ())
-    rust_error_at (type.get_locus (),
+    rust_error_at (type.get_locus (), ErrorCode::E0658,
 		   "mutable references are not allowed in constant functions");
 }
 
diff --git a/gcc/rust/checks/errors/rust-feature-gate.cc b/gcc/rust/checks/errors/rust-feature-gate.cc
index a90944e45ab1..29bc2fbea93c 100644
--- a/gcc/rust/checks/errors/rust-feature-gate.cc
+++ b/gcc/rust/checks/errors/rust-feature-gate.cc
@@ -86,7 +86,7 @@ FeatureGate::gate (Feature::Name name, location_t loc,
 	{
 	  const char *fmt_str
 	    = "%s. add `#![feature(%s)]` to the crate attributes to enable.";
-	  rust_error_at (loc, fmt_str, error_msg.c_str (),
+	  rust_error_at (loc, ErrorCode::E0658, fmt_str, error_msg.c_str (),
 			 feature.as_string ().c_str ());
 	}
     }