diff --git a/CHANGELOG.md b/CHANGELOG.md
index fcec033..a03e57b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ### Unreleased
 
+- Allow a client certificate subject's CN to be blank.
+
 ### v0.2.2 (2012-03-31)
 
 - Fix a regression in path matching for the static directory application.
diff --git a/jetforce.py b/jetforce.py
index 8f33a9a..79aa538 100755
--- a/jetforce.py
+++ b/jetforce.py
@@ -529,7 +529,7 @@ class GeminiRequestHandler:
             environ.update(
                 {
                     "AUTH_TYPE": "CERTIFICATE",
-                    "REMOTE_USER": subject["commonName"],
+                    "REMOTE_USER": subject.get("commonName", ""),
                     "TLS_CLIENT_NOT_BEFORE": self.client_cert["notBefore"],
                     "TLS_CLIENT_NOT_AFTER": self.client_cert["notAfter"],
                     "TLS_CLIENT_SERIAL_NUMBER": self.client_cert["serialNumber"],