diff --git a/src/_zkapauthorizer/_plugin.py b/src/_zkapauthorizer/_plugin.py
index 1ce34fed2774c545296ecf5ad330a32c8c3e2281..e63b05a84f5f38cc3731349c81c985e7bc50292d 100644
--- a/src/_zkapauthorizer/_plugin.py
+++ b/src/_zkapauthorizer/_plugin.py
@@ -145,7 +145,7 @@ class ZKAPAuthorizer(object):
         signing_key = SigningKey.decode_base64(
             FilePath(
                 kwargs.pop(u"ristretto-signing-key-path"),
-            ).getContent(),
+            ).getContent().strip(),
         )
         announcement = {
             u"ristretto-issuer-root-url": root_url,