diff --git a/src/spid_sp_test/metadata_extra.py b/src/spid_sp_test/metadata_extra.py
index 13c6d12..c4d57ba 100644
--- a/src/spid_sp_test/metadata_extra.py
+++ b/src/spid_sp_test/metadata_extra.py
@@ -105,10 +105,12 @@ def test_Signature_extra(self):
 
                 self._assertTrue(
                     (
-                        datetime.datetime.strptime(sign_cert[3], "%b %d %H:%M:%S %Y")
-                        >= datetime.datetime.now()
+                        datetime.datetime != "" and ( 
+                            datetime.datetime.strptime(sign_cert[3], "%b %d %H:%M:%S %Y")
+                            >= datetime.datetime.now()
+                        )
                     ),
-                    f"The certificate #{i} is expired. It was valid till {sign_cert[3]}",
+                    f"The certificate #{i} is expired or datetime is not valid. It was valid till {sign_cert[3]}",
                     **_data,
                 )
                 os.remove(fname)