diff --git a/rules/rules_test.go b/rules/rules_test.go
index a3867b94fd908900a1fb4cc92f7eadb654c6de9c..2331c51b44ed6cbbaa60620f29a4fa6ed9c8c032 100644
--- a/rules/rules_test.go
+++ b/rules/rules_test.go
@@ -46,6 +46,13 @@ func TestConverts(t *testing.T) {
 			"f",
 			71.6,
 		},
+		{
+			"k to f",
+			22.0,
+			"k",
+			"f",
+			-420.07,
+		},
 	}
 
 	ngn, err := New()