diff --git a/authority/config/config.go b/authority/config/config.go
index b13b3e36..bd61369e 100644
--- a/authority/config/config.go
+++ b/authority/config/config.go
@@ -90,7 +90,7 @@ type CRLConfig struct {
 	GenerateOnRevoke bool                  `json:"generateOnRevoke,omitempty"`
 	CacheDuration    *provisioner.Duration `json:"cacheDuration,omitempty"`
 	RenewPeriod      *provisioner.Duration `json:"renewPeriod,omitempty"`
-	IDPurl           string                `json:"idpurl"`
+	IDPurl           string                `json:"idpurl,omitempty"`
 }
 
 // IsEnabled returns if the CRL is enabled.