diff --git a/og_register/og_register.module b/og_register/og_register.module
index ca7c23a..dd428eb 100644
--- a/og_register/og_register.module
+++ b/og_register/og_register.module
@@ -48,6 +48,9 @@
     if (!is_array($condition)) {
       continue;
     }
+    if (!is_string($condition['field'])) {
+      continue;
+    }
     if ($condition['field'] != $group_type . '.' . $entity_info['entity keys']['id']) {
       continue;
     }