diff --git a/test/property/test_port_out_pin.rb b/test/property/test_port_out_pin.rb
index 039717872ada7a48de2c81f135eb3d05dca7680d..1d8a0cfaa122ad2ab24ee246c6f0aa4c176b580e 100644
--- a/test/property/test_port_out_pin.rb
+++ b/test/property/test_port_out_pin.rb
@@ -144,4 +144,23 @@ class PortOutPinPropertyTest < Minitest::Test
 		}
 	end
 	em :test_complete_mismatched_pins_returns_error
+
+	def test_complete_invalid_pin_format_returns_error
+		property_of {
+			PortOutPinCompleteCmd
+				.new(REDIS)
+				.pin { choose("ab", "a" * 11, "pin!@#") }
+				.confirm_pin { |pin| pin }
+				.generate
+		}.check { |_metadata, example|
+			process_stanza(example['stanza'])
+
+			assert_equal 1, written.length
+			reply = written.shift
+			assert_kind_of Blather::StanzaError, reply
+			assert_equal :modify, reply.type
+			assert_equal :bad_request, reply.name
+		}
+	end
+	em :test_complete_invalid_pin_format_returns_error
 end