diff --git a/lib/WeBWorK/Authen/LTIAdvantage.pm b/lib/WeBWorK/Authen/LTIAdvantage.pm
index 9dca92eb29..3927584e2e 100644
--- a/lib/WeBWorK/Authen/LTIAdvantage.pm
+++ b/lib/WeBWorK/Authen/LTIAdvantage.pm
@@ -159,17 +159,26 @@ sub get_credentials ($self) {
 		return $value;
 	};
 
-	if (my $user_id = $extract_claim->($ce->{LTI}{v1p3}{preferred_source_of_username})) {
-		$user_id_source  = $ce->{LTI}{v1p3}{preferred_source_of_username};
-		$type_of_source  = 'preferred_source_of_username';
-		$self->{user_id} = $user_id;
-	}
+	# First check if there is a user with the current LMS user id saved in the lis_source_did column.
+	if ($claims->{sub} && (my $user = ($c->db->getUsersWhere({ lis_source_did => $claims->{sub} }))[0])) {
+		$user_id_source  = 'database';
+		$type_of_source  = 'existing database user';
+		$self->{user_id} = $user->user_id;
+	} else {
+		if (my $user_id = $extract_claim->($ce->{LTI}{v1p3}{preferred_source_of_username})) {
+			$user_id_source  = $ce->{LTI}{v1p3}{preferred_source_of_username};
+			$type_of_source  = "$user_id_source which was preferred_source_of_username";
+			$self->{user_id} = $user_id;
+		}
 
-	# Fallback if necessary
-	if (!defined $self->{user_id} && (my $user_id = $extract_claim->($ce->{LTI}{v1p3}{fallback_source_of_username}))) {
-		$user_id_source  = $ce->{LTI}{v1p3}{fallback_source_of_username};
-		$type_of_source  = 'fallback_source_of_username';
-		$self->{user_id} = $user_id;
+		# Fallback if necessary
+		if (!defined $self->{user_id}
+			&& (my $user_id = $extract_claim->($ce->{LTI}{v1p3}{fallback_source_of_username})))
+		{
+			$user_id_source  = $ce->{LTI}{v1p3}{fallback_source_of_username};
+			$type_of_source  = "$user_id_source which was fallback_source_of_username";
+			$self->{user_id} = $user_id;
+		}
 	}
 
 	if ($self->{user_id}) {
@@ -196,7 +205,7 @@ sub get_credentials ($self) {
 		# For setting up it is helpful to print out what is believed to be the user id and address is at this point.
 		if ($ce->{debug_lti_parameters}) {
 			warn "=========== SUMMARY ============\n";
-			warn "User id is |$self->{user_id}| (obtained from $user_id_source which was $type_of_source)\n";
+			warn "User id is |$self->{user_id}| (obtained from $type_of_source)\n";
 			warn "User email address is |$self->{email}|\n";
 			warn "strip_domain_from_email is |", $ce->{LTI}{v1p3}{strip_domain_from_email} // 0, "|\n";
 			warn "Student id is |$self->{student_id}|\n";
@@ -419,6 +428,7 @@ sub create_user ($self) {
 	$newUser->recitation($self->{recitation} // '');
 	$newUser->comment(formatDateTime(time, 0, $ce->{siteDefaults}{timezone}, $ce->{language}));
 	$newUser->student_id($self->{student_id} // '');
+	$newUser->lis_source_did($c->stash->{lti_lms_user_id}) if $c->stash->{lti_lms_user_id};
 
 	# Allow sites to customize the user.
 	$ce->{LTI}{v1p3}{modify_user}($self, $newUser) if ref($ce->{LTI}{v1p3}{modify_user}) eq 'CODE';
@@ -508,6 +518,7 @@ sub maybe_update_user ($self) {
 		$tempUser->section($self->{section}       // '');
 		$tempUser->recitation($self->{recitation} // '');
 		$tempUser->student_id($self->{student_id} // '');
+		$tempUser->lis_source_did($c->stash->{lti_lms_user_id}) if $c->stash->{lti_lms_user_id};
 
 		# Allow sites to customize the temp user
 		$ce->{LTI}{v1p3}{modify_user}($self, $tempUser) if ref($ce->{LTI}{v1p3}{modify_user}) eq 'CODE';