diff --git a/tasks/configure.yml b/tasks/configure.yml
index 1cd84a4..743bcc3 100644
--- a/tasks/configure.yml
+++ b/tasks/configure.yml
@@ -21,7 +21,7 @@
   set_fact:
     opendkim_genkey_cmd: "{{ where_result.stdout }}"
   when:
-    - stdout in where_result
+    - "'stdout' in where_result"
     - where_result.stdout != ''
 
 - name: Fail if opendkim-genkey is not found