diff --git a/CMakeLists.txt b/CMakeLists.txt
index b480515..05fbc17 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -97,16 +97,16 @@ add_definitions(-DQT_NO_KEYWORDS)
 option(KDEPIM_RUN_AKONADI_TEST "Enable autotest based on Akonadi." TRUE)
 
 # Not supported yet
-#option(USE_UNITY_CMAKE_SUPPORT "Use UNITY cmake support (speedup compile time)" FALSE)
-
-#set(COMPILE_WITH_UNITY_CMAKE_SUPPORT false)
-#if (USE_UNITY_CMAKE_SUPPORT)
-#    if(${CMAKE_VERSION} VERSION_LESS "3.16.0")
-#        message(STATUS "CMAKE version is less than 3.16.0 . We can't use cmake unify build support")
-#    else()
-#        set(COMPILE_WITH_UNITY_CMAKE_SUPPORT true)
-#    endif()
-#endif()
+option(USE_UNITY_CMAKE_SUPPORT "Use UNITY cmake support (speedup compile time)" FALSE)
+
+set(COMPILE_WITH_UNITY_CMAKE_SUPPORT false)
+if (USE_UNITY_CMAKE_SUPPORT)
+    if(${CMAKE_VERSION} VERSION_LESS "3.16.0")
+        message(STATUS "CMAKE version is less than 3.16.0 . We can't use cmake unify build support")
+    else()
+        set(COMPILE_WITH_UNITY_CMAKE_SUPPORT true)
+    endif()
+endif()
 
 add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0x050f00)
 add_definitions(-DKF_DISABLE_DEPRECATED_BEFORE_AND_AT=0x054F00)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f90e10b..c565b5a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -234,6 +234,7 @@ qt5_add_dbus_interfaces(libmailcommon_SRCS ${CMAKE_CURRENT_SOURCE_DIR}/dbusinter
 add_library(KF5MailCommon ${libmailcommon_SRCS})
 if (COMPILE_WITH_UNITY_CMAKE_SUPPORT)
     set_target_properties(KF5MailCommon PROPERTIES UNITY_BUILD ON)
+    set_source_files_properties(${libmailcommon_search_SRCS} PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)
 endif()
 generate_export_header(KF5MailCommon BASE_NAME mailcommon)