diff --git a/pkg/apis/certmanager/v1/types_issuer.go b/pkg/apis/certmanager/v1/types_issuer.go
index 464ff3e3a..7f5772e95 100644
--- a/pkg/apis/certmanager/v1/types_issuer.go
+++ b/pkg/apis/certmanager/v1/types_issuer.go
@@ -93,6 +93,8 @@ type IssuerSpec struct {
 	IssuerConfig `json:",inline"`
 }
 
+// IssuerConfig includes any configuration required for the issuer.
+// only one of these can be set per issuer.
 type IssuerConfig struct {
 	// ACME configures this issuer to communicate with a RFC8555 (ACME) server
 	// to obtain signed x509 certificates.
diff --git a/pkg/apis/certmanager/v1alpha2/types_issuer.go b/pkg/apis/certmanager/v1alpha2/types_issuer.go
index 0eb6e2136..551f9ed06 100644
--- a/pkg/apis/certmanager/v1alpha2/types_issuer.go
+++ b/pkg/apis/certmanager/v1alpha2/types_issuer.go
@@ -89,6 +89,8 @@ type IssuerSpec struct {
 	IssuerConfig `json:",inline"`
 }
 
+// IssuerConfig includes any configuration required for the issuer.
+// only one of these can be set per issuer.
 type IssuerConfig struct {
 	// ACME configures this issuer to communicate with a RFC8555 (ACME) server
 	// to obtain signed x509 certificates.
diff --git a/pkg/apis/certmanager/v1alpha3/types_issuer.go b/pkg/apis/certmanager/v1alpha3/types_issuer.go
index fa07b79dd..65a0b28a2 100644
--- a/pkg/apis/certmanager/v1alpha3/types_issuer.go
+++ b/pkg/apis/certmanager/v1alpha3/types_issuer.go
@@ -89,6 +89,8 @@ type IssuerSpec struct {
 	IssuerConfig `json:",inline"`
 }
 
+// IssuerConfig includes any configuration required for the issuer.
+// only one of these can be set per issuer.
 type IssuerConfig struct {
 	// ACME configures this issuer to communicate with a RFC8555 (ACME) server
 	// to obtain signed x509 certificates.
diff --git a/pkg/apis/certmanager/v1beta1/types_issuer.go b/pkg/apis/certmanager/v1beta1/types_issuer.go
index ba9488ba6..1d7b88d18 100644
--- a/pkg/apis/certmanager/v1beta1/types_issuer.go
+++ b/pkg/apis/certmanager/v1beta1/types_issuer.go
@@ -91,6 +91,8 @@ type IssuerSpec struct {
 	IssuerConfig `json:",inline"`
 }
 
+// IssuerConfig includes any configuration required for the issuer.
+// only one of these can be set per issuer.
 type IssuerConfig struct {
 	// ACME configures this issuer to communicate with a RFC8555 (ACME) server
 	// to obtain signed x509 certificates.