diff --git a/modules/icon_filter/icon_filter.module b/modules/icon_filter/icon_filter.module
index bebfb35..51f344b 100644
--- a/modules/icon_filter/icon_filter.module
+++ b/modules/icon_filter/icon_filter.module
@@ -61,7 +61,9 @@ function icon_filter_preprocess_field(&$variables) {
   $element = &$variables['element'];
   if (!empty($element['#formatter'])) {
     foreach ($element['#items'] as &$item) {
-      if (!empty($item['format']) && ($filters = filter_list_format($item['format'])) && !empty($filters['icon']->status)) {
+      // Fields like relation select from relation module will have items as stdClass objects.
+      // Filter them out using is_array() check.
+      if (is_array($item) && !empty($item['format']) && ($filters = filter_list_format($item['format'])) && !empty($filters['icon']->status)) {
         if (preg_match_all(ICON_FILTER_REGEX, $item['value'], $matches, PREG_SET_ORDER)) {
           foreach ($matches as $match) {
             if (!isset($icons[$match[0]]) && ($bundle = icon_bundle_load($match[1]))) {