diff --git a/src/test/MigrationTest/QemuMigrateMock.pm b/src/test/MigrationTest/QemuMigrateMock.pm
index 3a48381..c715a60 100644
--- a/src/test/MigrationTest/QemuMigrateMock.pm
+++ b/src/test/MigrationTest/QemuMigrateMock.pm
@@ -21,6 +21,7 @@ my $QM_LIB_PATH = $ENV{QM_LIB_PATH} or die "no QM_LIB_PATH set\n";
 
 my $source_volids = decode_json(file_get_contents("${RUN_DIR_PATH}/source_volids"));
 my $source_vdisks = decode_json(file_get_contents("${RUN_DIR_PATH}/source_vdisks"));
+my $source_other_volumes = decode_json(file_get_contents("${RUN_DIR_PATH}/source_other_volumes"));
 my $vm_status = decode_json(file_get_contents("${RUN_DIR_PATH}/vm_status"));
 my $expected_calls = decode_json(file_get_contents("${RUN_DIR_PATH}/expected_calls"));
 my $fail_config = decode_json(file_get_contents("${RUN_DIR_PATH}/fail_config"));
@@ -304,11 +305,11 @@ $MigrationTest::Shared::storage_module->mock(
         my ($scfg, $volid) = @_;
         my ($storeid, $volname) = PVE::Storage::parse_volume_id($volid);
 
-        for my $v ($source_vdisks->{$storeid}->@*) {
+        for my $v ($source_vdisks->{$storeid}->@*, $source_other_volumes->{$storeid}->@*) {
             return wantarray ? ($v->{size}, $v->{format}, $v->{used}, $v->{parent}) : $v->{size}
                 if $v->{volid} eq $volid;
         }
-        die "could not find '$volid' in mock 'source_vdisks'\n";
+        die "could not find '$volid' in mock 'source_vdisks' or 'source_other_volumes'\n";
     },
 );
 
diff --git a/src/test/run_qemu_migrate_tests.pl b/src/test/run_qemu_migrate_tests.pl
index 05eed1d..13962f7 100644
--- a/src/test/run_qemu_migrate_tests.pl
+++ b/src/test/run_qemu_migrate_tests.pl
@@ -436,6 +436,10 @@ my $source_vdisks = {
     ],
 };
 
+# non-image volumes on the source, e.g. ISO images, in the same format as $source_vdisks. They
+# are only used for the mocked volume_size_info(), because vdisk_list() only returns images.
+my $source_other_volumes = {};
+
 my $default_expected_calls_online = {
     move_config_to_node => 1,
     ssh_qm_start => 1,
@@ -1732,6 +1736,7 @@ foreach my $test (@{$tests}) {
     file_set_contents("${run_dir}/replication_config", to_json($replication_config));
     file_set_contents("${run_dir}/storage_config", to_json($storage_config));
     file_set_contents("${run_dir}/source_vdisks", to_json($source_vdisks));
+    file_set_contents("${run_dir}/source_other_volumes", to_json($source_other_volumes));
 
     my $expect_die = $test->{expect_die};
     my $expected = $test->{expected};