diff --git a/src/pf_tests/test_mo_datetime.pf b/src/pf_tests/test_mo_datetime.pf
index a3276a536ae8929436a9aa0400aced18a092754c..b82b7fdb49d74479cd4d9e4b2271b0bf633c8eb5 100644
--- a/src/pf_tests/test_mo_datetime.pf
+++ b/src/pf_tests/test_mo_datetime.pf
@@ -252,7 +252,8 @@ contains
     @assertTrue(datetime("1992-10-08 15:15:00") == datetime("1992-10-08 15:15"))
     @assertTrue(datetime("1992-10-08 15:00:00") == datetime("1992-10-08 15"))
     @assertTrue(datetime("1992-10-08T00:00:00") == datetime("1992-10-08"))
-    @assertTrue(datetime("1992-10-08T00:00:00") == datetime("1992-10-08"))
+    @assertTrue(datetime("1992-10-01T00:00:00") == datetime("1992-10"))
+    @assertTrue(datetime("1992-01-01T00:00:00") == datetime("1992"))
     @assertTrue(datetime("1992-10-01 15:15:00") == datetime("1992-10T15:15"))
     @assertTrue(datetime("1992-01-01 15:15:00") == datetime("1992 15:15"))