diff --git a/promenade/pki.py b/promenade/pki.py
index 605c3284..1ee9c309 100644
--- a/promenade/pki.py
+++ b/promenade/pki.py
@@ -193,7 +193,8 @@ class block_literal(str):
 
 
 def block_literal_representer(dumper, data):
-    return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='|')
+    return dumper.represent_scalar(
+        'tag:yaml.org,2002:str', str(data), style='|')
 
 
 yaml.add_representer(block_literal, block_literal_representer)