diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index ee26510..57c2750 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -806,3 +806,27 @@ function comment_entity_view_display_presave(EntityViewDisplayInterface $display
     }
   }
 }
+
+/**
+ * Implements hook_theme_registry_alter
+ */
+function comment_theme_registry_alter(&$theme_registry) {
+  // See https://www.drupal.org/node/2866208
+  // This fixes a problem caused by the fact that the comment entity and the
+  // field defined in this module both have an id of "comment". The problem
+  // happens when a preprocess hook is defined for a field in the comment
+  // entity but no specific template is created.
+  foreach($theme_registry as $key => $info) {
+    if (strpos($key, 'field__comment__') !== 0) {
+      continue;
+    }
+
+    // If we're here then it must be for a field in the comment entity, not the
+    // field called comment. field--comment is the template for the field
+    // called comment. It is of no use for fields within the comment entity.
+    // Let's fall back to the "field" template.
+    if ($info['template'] === 'field--comment') {
+      $theme_registry[$key]['template'] = 'field';
+    }
+  }
+}