diff --git a/lib/et-orbi/time.rb b/lib/et-orbi/time.rb
index cf531e9..5f7a870 100644
--- a/lib/et-orbi/time.rb
+++ b/lib/et-orbi/time.rb
@@ -471,7 +471,7 @@ def strfz(code)
 
     def _to_f(o)
 
-      fail ArgumentError(
+      fail ArgumentError.new(
         "Comparison of EoTime with #{o.inspect} failed"
       ) unless o.respond_to?(:to_f)
 
diff --git a/test/eo_time_test.rb b/test/eo_time_test.rb
index c9fc480..a9d5ddb 100644
--- a/test/eo_time_test.rb
+++ b/test/eo_time_test.rb
@@ -916,6 +916,19 @@
         assert t0.send(comparator, t1), asserted
       end
     end
+
+    test 'rejects unsupported comparison operands with ArgumentError' do
+
+      ot = EtOrbi::EoTime.new(0, 'UTC')
+      operand = Object.new
+
+      [ :<, :<=, :>, :>=, :<=> ].each do |comparator|
+
+        assert_error(
+          lambda { ot.send(comparator, operand) },
+          ArgumentError)
+      end
+    end
   end
 end