diff --git a/src/private/protocol.cpp b/src/private/protocol.cpp
--- a/src/private/protocol.cpp
+++ b/src/private/protocol.cpp
@@ -331,6 +331,12 @@
 
 /******************************************************************************/
 
+Response::Response()
+    : Command(Command::Invalid | Command::_ResponseBit)
+    , mErrorCode(0)
+{
+}
+
 Response::Response(Command::Type type)
     : Command(type | Command::_ResponseBit)
     , mErrorCode(0)
diff --git a/src/private/protocol_p.h b/src/private/protocol_p.h
--- a/src/private/protocol_p.h
+++ b/src/private/protocol_p.h
@@ -200,7 +200,7 @@
 class AKONADIPRIVATE_EXPORT Response : public Command
 {
 public:
-    explicit Response() = default;
+    explicit Response();
     explicit Response(const Response &) = default;
     Response(Response &&) = default;
     Response &operator=(const Response &) = default;