--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,3 +7,6 @@
         KF5::CalendarCore)
 
 add_test(tst_engine tst_engine)
+
+set_tests_properties(tst_engine
+                     PROPERTIES ENVIRONMENT "QT_PLUGIN_PATH=${CMAKE_BINARY_DIR}/")