diff --git a/gcc/rust/checks/errors/rust-ast-validation.cc b/gcc/rust/checks/errors/rust-ast-validation.cc
index 477e889c5129..7555abc449cc 100644
--- a/gcc/rust/checks/errors/rust-ast-validation.cc
+++ b/gcc/rust/checks/errors/rust-ast-validation.cc
@@ -116,6 +116,16 @@ ASTValidation::visit (AST::Function &function)
   AST::ContextualASTVisitor::visit (function);
 }
 
+void
+ASTValidation::visit (AST::TraitFunctionDecl &decl)
+{
+  const auto &qualifiers = decl.get_qualifiers ();
+
+  if (context.back () == Context::TRAIT && qualifiers.is_const ())
+    rust_error_at (decl.get_identifier ().get_locus (), ErrorCode::E0379,
+		   "functions in traits cannot be declared const");
+}
+
 void
 ASTValidation::visit (AST::Trait &trait)
 {
diff --git a/gcc/rust/checks/errors/rust-ast-validation.h b/gcc/rust/checks/errors/rust-ast-validation.h
index 1052168ea728..f1c3018d142d 100644
--- a/gcc/rust/checks/errors/rust-ast-validation.h
+++ b/gcc/rust/checks/errors/rust-ast-validation.h
@@ -41,6 +41,7 @@ class ASTValidation : public AST::ContextualASTVisitor
   virtual void visit (AST::Union &item);
   virtual void visit (AST::Function &function);
   virtual void visit (AST::Trait &trait);
+  virtual void visit (AST::TraitFunctionDecl &decl);
 };
 
 } // namespace Rust