diff --git a/resources/mbox/CMakeLists.txt b/resources/mbox/CMakeLists.txt
index b28fb4e37..c6fa6938f 100644
--- a/resources/mbox/CMakeLists.txt
+++ b/resources/mbox/CMakeLists.txt
@@ -1,78 +1,82 @@
 
 add_subdirectory(wizard)
 
 set(mboxresource_common_SRCS
     deleteditemsattribute.cpp
 )
 kconfig_add_kcfg_files(mboxresource_common_SRCS settings.kcfgc)
 
 ################################## Resource #################################
 add_definitions(-DTRANSLATION_DOMAIN=\"akonadi_mbox_resource\")
 
 set( mboxresource_SRCS
   mboxresource.cpp
   ${mboxresource_common_SRCS}
 )
 
+# Fix a race condition. mboxresource.cpp needs compactpage.h which includes ui_compactpage.h.
+# Make sure the ui file is generated before building the akonadi_mbox_resource target.
+set_source_files_properties(mboxresource.cpp PROPERTIES OBJECT_DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/ui_compactpage.h)
+
 ecm_qt_declare_logging_category(mboxresource_SRCS HEADER mboxresource_debug.h IDENTIFIER MBOXRESOURCE_LOG CATEGORY_NAME org.kde.pim.mboxresource)
 
 install( FILES mboxresource.desktop DESTINATION "${KDE_INSTALL_DATAROOTDIR}/akonadi/agents" )
 
 kcfg_generate_dbus_interface(${CMAKE_CURRENT_SOURCE_DIR}/mboxresource.kcfg org.kde.Akonadi.Mbox.Settings)
 qt5_add_dbus_adaptor(mboxresource_SRCS
   ${CMAKE_CURRENT_BINARY_DIR}/org.kde.Akonadi.Mbox.Settings.xml settings.h Settings
 )
 
 add_executable(akonadi_mbox_resource ${mboxresource_SRCS})
 
 if( APPLE )
   set_target_properties(akonadi_mbox_resource PROPERTIES MACOSX_BUNDLE_INFO_PLIST ${CMAKE_CURRENT_SOURCE_DIR}/../Info.plist.template)
   set_target_properties(akonadi_mbox_resource PROPERTIES MACOSX_BUNDLE_GUI_IDENTIFIER "org.kde.Akonadi.Mbox")
   set_target_properties(akonadi_mbox_resource PROPERTIES MACOSX_BUNDLE_BUNDLE_NAME "KDE Akonadi Mbox Resource")
 endif ()
 
 target_link_libraries(akonadi_mbox_resource
     KF5::I18n
     KF5::Mbox
     KF5::AkonadiCore
     KF5::AkonadiMime
     KF5::KIOCore
     KF5::Mime
     KF5::AkonadiAgentBase
     KF5::DBusAddons
     KF5::Completion
     akonadi-singlefileresource
 )
 
 install(TARGETS akonadi_mbox_resource ${KDE_INSTALL_TARGETS_DEFAULT_ARGS})
 if (BUILD_TESTING)
    add_subdirectory(autotests)
 endif()
 
 ############################# Config plugin ################################
 
 set(mboxconfig_SRCS
     mboxconfig.cpp
     lockmethodpage.cpp
     compactpage.cpp
     ${mboxresource_common_SRCS}
 )
 
 ki18n_wrap_ui(mboxconfig_SRCS
   compactpage.ui
   lockfilepage.ui
 )
 
 kcoreaddons_add_plugin(mboxconfig
     SOURCES ${mboxconfig_SRCS}
     JSON "mboxconfig.json"
     INSTALL_NAMESPACE "akonadi/config"
 )
 target_link_libraries(mboxconfig
     KF5::AkonadiCore
     KF5::ConfigWidgets
     KF5::KIOWidgets
     KF5::I18n
     KF5::Mbox
     akonadi-singlefileresource
 )