diff --git a/test/message/append.cpp b/test/message/append.cpp
index 4f85b74..84dcc28 100644
--- a/test/message/append.cpp
+++ b/test/message/append.cpp
@@ -142,6 +142,31 @@
         b.call_noreply(m);
     }
 
+    // Test double and bool.
+    {
+        auto m = newMethodCall__test(b);
+        bool t = true;
+        m.append(t, true, false, 1.1);
+        verifyTypeString = "bbbd";
+
+        struct verify
+        {
+            static void op(sd_bus_message* m)
+            {
+                bool t1, t2, f1;
+                double d;
+                sd_bus_message_read(m, "bbbd", &t1, &t2, &f1, &d);
+                assert(t1);
+                assert(t2);
+                assert(!f1);
+                assert(d == 1.1);
+            }
+        };
+        verifyCallback = &verify::op;
+
+        b.call_noreply(m);
+    }
+
     // Test r-value string.
     {
         auto m = newMethodCall__test(b);