diff --git a/src/library/coercion.cpp b/src/library/coercion.cpp
index 1eb1eb359..73ae0115a 100644
--- a/src/library/coercion.cpp
+++ b/src/library/coercion.cpp
@@ -298,9 +298,9 @@ environment add_coercion(environment const & env, name const & f, name const & C
             expr fn = mk_constant(f, const_levels(C_fn));
             optional<coercion_class> cls = type_to_coercion_class(binding_body(t));
             if (!cls)
-                throw exception(sstream() << "invalid coercion, '" << f << "' does not have the expected type to be used as a coercion");
+                throw exception(sstream() << "invalid coercion, '" << f << "' cannot be used as a coercion from '" << C << "'");
             else if (cls->kind() == coercion_class_kind::User && cls->get_name() == C)
-                throw exception(sstream() << "invalid coercion, '" << f << "' is a coercion from '" << C << "' on itself");
+                throw exception(sstream() << "invalid coercion, '" << f << "' is a coercion from '" << C << "' to itself");
             return add_coercion(env, C, fn, d.get_type(), d.get_params(), num, *cls, ios);
         }
         t = binding_body(t);
@@ -317,7 +317,7 @@ environment add_coercion(environment const & env, name const & f, io_state const
         t = binding_body(t);
     expr C = get_app_fn(binding_domain(t));
     if (!is_constant(C))
-        throw exception(sstream() << "invalid coercion, '" << f << "' does not have the expected type to be used as a coercion");
+        throw exception(sstream() << "invalid coercion, '" << f << "' cannot be used as a coercion");
     return add_coercion(env, f, const_name(C), ios);
 }
 
diff --git a/tests/lua/coe4.lua b/tests/lua/coe4.lua
new file mode 100644
index 000000000..c2085815d
--- /dev/null
+++ b/tests/lua/coe4.lua
@@ -0,0 +1,23 @@
+local env    = environment()
+local l      = param_univ("l")
+local Ul     = mk_sort(l)
+local lst_l  = Const("lst", {l})
+local A      = Local("A", Ul)
+env = add_decl(env, mk_var_decl("lst", {l}, mk_arrow(Ul, Ul)))
+env = add_decl(env, mk_var_decl("lst2lst", {l}, Pi(A, mk_arrow(lst_l(A), lst_l(A)))))
+env = add_decl(env, mk_var_decl("head", {l}, Pi(A, mk_arrow(lst_l(A), A))))
+env = add_decl(env, mk_var_decl("id", {l}, Pi(A, mk_arrow(A, A))))
+function add_bad_coercion(env, c)
+   ok, msg = pcall(function() add_coercion(env, c) end)
+   assert(not ok)
+   print("Expected error: " .. tostring(msg:what()))
+end
+function add_bad_coercion2(env, c, cls)
+   ok, msg = pcall(function() add_coercion(env, c, cls) end)
+   assert(not ok)
+   print("Expected error: " .. tostring(msg:what()))
+end
+add_bad_coercion(env, "lst2lst")
+add_bad_coercion(env, "head")
+add_bad_coercion(env, "id")
+add_bad_coercion2(env, "head", "lst")