diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -55,7 +55,7 @@
    link_libraries("asan")
 endif()
 
-add_definitions(-DQT_USE_FAST_CONCATENATION -DQT_USE_FAST_OPERATOR_PLUS)
+add_definitions(-DQT_USE_FAST_CONCATENATION -DQT_USE_FAST_OPERATOR_PLUS -DQT_NO_URL_CAST_FROM_STRING)
 include_directories (
     ${CMAKE_SOURCE_DIR}
     ${CMAKE_BINARY_DIR}
diff --git a/src/akonadi/akonadiserializer.cpp b/src/akonadi/akonadiserializer.cpp
--- a/src/akonadi/akonadiserializer.cpp
+++ b/src/akonadi/akonadiserializer.cpp
@@ -226,7 +226,7 @@
                    [&mimeDb] (const KCalCore::Attachment::Ptr &attach) {
                        Domain::Task::Attachment attachment;
                        if (attach->isUri())
-                           attachment.setUri(attach->uri());
+                           attachment.setUri(QUrl(attach->uri()));
                        else
                            attachment.setData(attach->decodedData());
                        attachment.setLabel(attach->label());