diff --git a/lemonldap-ng-common/lib/Lemonldap/NG/Common/Combination/Parser.pm b/lemonldap-ng-common/lib/Lemonldap/NG/Common/Combination/Parser.pm
index 58e49b253dd2533475c1f3df2de375d9c59bbecb..241eb59129fb19609409920264aac0c37ba8c0ce 100644
--- a/lemonldap-ng-common/lib/Lemonldap/NG/Common/Combination/Parser.pm
+++ b/lemonldap-ng-common/lib/Lemonldap/NG/Common/Combination/Parser.pm
@@ -88,12 +88,12 @@ sub parseAnd {
                     my ( $r, $name ) = $obj->(@_);
 
                     # Case "string" (form type)
-                    if ( $r & ~$r ) {
+                    if ( $r && $r & ~$r ) {
                         $str{$r}++;
                     }
                     else {
                         return ( wantarray ? ( $r, $name ) : $r )
-                          unless ( $r == PE_OK );
+                          unless ( !$r || $r == PE_OK );
                     }
                 }
                 my $res = %str ? join( ',', keys %str ) : PE_OK;
diff --git a/lemonldap-ng-portal/lib/Lemonldap/NG/Portal/2F/Yubikey.pm b/lemonldap-ng-portal/lib/Lemonldap/NG/Portal/2F/Yubikey.pm
index 3735bbf0f132fb89c2d43c8f41d3e59d71777b62..15909872dce4eb58d1c36c913098003db3a49218 100644
--- a/lemonldap-ng-portal/lib/Lemonldap/NG/Portal/2F/Yubikey.pm
+++ b/lemonldap-ng-portal/lib/Lemonldap/NG/Portal/2F/Yubikey.pm
@@ -122,7 +122,7 @@ sub _findYubikey {
         }
     }
 
-    return $yubikey;
+    return $yubikey || '';
 
 }
 
diff --git a/lemonldap-ng-portal/t/01-WebAuthn.t b/lemonldap-ng-portal/t/01-WebAuthn.t
index a713289f2d163cb8b48f9b97f267aed3c5d8537d..1e7d4632da3555f2eef3f5b338160033121becd3 100644
--- a/lemonldap-ng-portal/t/01-WebAuthn.t
+++ b/lemonldap-ng-portal/t/01-WebAuthn.t
@@ -80,7 +80,7 @@ ENDKEY
       expectForm( $res, "", '/webauthn2fcheck', 'token', 'credential' );
 
     my ($json) = $res->[2]->[0] =~
-      m#<script type="application/init">\s*({"request"[^<]*})\s*</script>#ms;
+      m#<script type="application/init">\s*(\{"request"[^<]*\})\s*</script>#ms;
     ok( $json, "Found request object in JS data" );
     $json = from_json($json);
     my $request   = $json->{request};