diff --git a/tests/SAML2/XML/md/EntityDescriptorTest.php b/tests/SAML2/XML/md/EntityDescriptorTest.php
index 0e7371d47..74f459b34 100644
--- a/tests/SAML2/XML/md/EntityDescriptorTest.php
+++ b/tests/SAML2/XML/md/EntityDescriptorTest.php
@@ -491,7 +491,7 @@ public function testUnmarshallingWithInvalidValidUntil(): void
 XML
         );
         $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('\'asdf\' is not a valid DateTime');
+        $this->expectExceptionMessage('\'asdf\' is not a valid xs:dateTime');
         EntityDescriptor::fromXML($document->documentElement);
     }
 
diff --git a/tests/SAML2/XML/mdrpi/PublicationInfoTest.php b/tests/SAML2/XML/mdrpi/PublicationInfoTest.php
index c469f71d1..51b07709d 100644
--- a/tests/SAML2/XML/mdrpi/PublicationInfoTest.php
+++ b/tests/SAML2/XML/mdrpi/PublicationInfoTest.php
@@ -86,7 +86,7 @@ public function testCreationInstantTimezoneNotZuluThrowsException(): void
         $document->setAttribute('creationInstant', '2011-01-01T00:00:00WT');
 
         $this->expectException(ProtocolViolationException::class);
-        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a valid DateTime");
+        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a DateTime expressed in the UTC timezone using the 'Z' timezone identifier.");
         PublicationInfo::fromXML($document);
     }
 
diff --git a/tests/SAML2/XML/mdrpi/PublicationTest.php b/tests/SAML2/XML/mdrpi/PublicationTest.php
index b2dd3755d..6245e63b5 100644
--- a/tests/SAML2/XML/mdrpi/PublicationTest.php
+++ b/tests/SAML2/XML/mdrpi/PublicationTest.php
@@ -80,7 +80,7 @@ public function testCreationInstantTimezoneNotZuluThrowsException(): void
         $document->setAttribute('creationInstant', '2011-01-01T00:00:00WT');
 
         $this->expectException(ProtocolViolationException::class);
-        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a valid DateTime");
+        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a DateTime expressed in the UTC timezone using the 'Z' timezone identifier.");
         Publication::fromXML($document);
     }
 
diff --git a/tests/SAML2/XML/mdrpi/RegistrationInfoTest.php b/tests/SAML2/XML/mdrpi/RegistrationInfoTest.php
index 3ae53db50..ec57b6eb2 100644
--- a/tests/SAML2/XML/mdrpi/RegistrationInfoTest.php
+++ b/tests/SAML2/XML/mdrpi/RegistrationInfoTest.php
@@ -104,7 +104,7 @@ public function testRegistrationInstantTimezoneNotZuluThrowsException(): void
         $document->setAttribute('registrationInstant', '2011-01-01T00:00:00WT');
 
         $this->expectException(ProtocolViolationException::class);
-        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a valid DateTime");
+        $this->expectExceptionMessage("'2011-01-01T00:00:00WT' is not a DateTime expressed in the UTC timezone using the 'Z' timezone identifier.");
         RegistrationInfo::fromXML($document);
     }