diff --git a/internal/apis/acme/v1/BUILD.bazel b/internal/apis/acme/v1/BUILD.bazel
index 2d97f838d..091228cfa 100644
--- a/internal/apis/acme/v1/BUILD.bazel
+++ b/internal/apis/acme/v1/BUILD.bazel
@@ -3,6 +3,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 go_library(
     name = "go_default_library",
     srcs = [
+        "conversion.go",
         "defaults.go",
         "doc.go",
         "register.go",
diff --git a/internal/apis/acme/v1/conversion.go b/internal/apis/acme/v1/conversion.go
new file mode 100644
index 000000000..ad5bbcbe8
--- /dev/null
+++ b/internal/apis/acme/v1/conversion.go
@@ -0,0 +1,36 @@
+/*
+Copyright 2021 The cert-manager Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	"k8s.io/apimachinery/pkg/conversion"
+
+	"github.com/jetstack/cert-manager/internal/apis/acme"
+	v1 "github.com/jetstack/cert-manager/pkg/apis/acme/v1"
+)
+
+// Convert_acme_ACMEIssuer_To_v1_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_acme_ACMEIssuer_To_v1_ACMEIssuer(in *acme.ACMEIssuer, out *v1.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_acme_ACMEIssuer_To_v1_ACMEIssuer(in, out, s)
+}
+
+// Convert_v1_ACMEIssuer_To_acme_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1_ACMEIssuer_To_acme_ACMEIssuer(in *v1.ACMEIssuer, out *acme.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_v1_ACMEIssuer_To_acme_ACMEIssuer(in, out, s)
+}
diff --git a/internal/apis/acme/v1alpha2/conversion.go b/internal/apis/acme/v1alpha2/conversion.go
index b3bbae61c..f20f039e2 100644
--- a/internal/apis/acme/v1alpha2/conversion.go
+++ b/internal/apis/acme/v1alpha2/conversion.go
@@ -82,3 +82,15 @@ func Convert_acme_OrderSpec_To_v1alpha2_OrderSpec(in *acme.OrderSpec, out *v1alp
 
 	return nil
 }
+
+// Convert_acme_ACMEIssuer_To_v1alpha2_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_acme_ACMEIssuer_To_v1alpha2_ACMEIssuer(in *acme.ACMEIssuer, out *v1alpha2.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_acme_ACMEIssuer_To_v1alpha2_ACMEIssuer(in, out, s)
+}
+
+// Convert_v1alpha2_ACMEIssuer_To_acme_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1alpha2_ACMEIssuer_To_acme_ACMEIssuer(in *v1alpha2.ACMEIssuer, out *acme.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_v1alpha2_ACMEIssuer_To_acme_ACMEIssuer(in, out, s)
+}
diff --git a/internal/apis/acme/v1alpha3/conversion.go b/internal/apis/acme/v1alpha3/conversion.go
index b98ba4432..4faebd31f 100644
--- a/internal/apis/acme/v1alpha3/conversion.go
+++ b/internal/apis/acme/v1alpha3/conversion.go
@@ -82,3 +82,15 @@ func Convert_acme_OrderSpec_To_v1alpha3_OrderSpec(in *acme.OrderSpec, out *v1alp
 
 	return nil
 }
+
+// Convert_acme_ACMEIssuer_To_v1alpha3_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_acme_ACMEIssuer_To_v1alpha3_ACMEIssuer(in *acme.ACMEIssuer, out *v1alpha3.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_acme_ACMEIssuer_To_v1alpha3_ACMEIssuer(in, out, s)
+}
+
+// Convert_v1alpha3_ACMEIssuer_To_acme_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1alpha3_ACMEIssuer_To_acme_ACMEIssuer(in *v1alpha3.ACMEIssuer, out *acme.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_v1alpha3_ACMEIssuer_To_acme_ACMEIssuer(in, out, s)
+}
diff --git a/internal/apis/acme/v1beta1/BUILD.bazel b/internal/apis/acme/v1beta1/BUILD.bazel
index 3d3141096..f88a791cb 100644
--- a/internal/apis/acme/v1beta1/BUILD.bazel
+++ b/internal/apis/acme/v1beta1/BUILD.bazel
@@ -3,6 +3,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 go_library(
     name = "go_default_library",
     srcs = [
+        "conversion.go",
         "defaults.go",
         "doc.go",
         "register.go",
diff --git a/internal/apis/acme/v1beta1/conversion.go b/internal/apis/acme/v1beta1/conversion.go
new file mode 100644
index 000000000..d5cfbd42a
--- /dev/null
+++ b/internal/apis/acme/v1beta1/conversion.go
@@ -0,0 +1,36 @@
+/*
+Copyright 2021 The cert-manager Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1beta1
+
+import (
+	"k8s.io/apimachinery/pkg/conversion"
+
+	"github.com/jetstack/cert-manager/internal/apis/acme"
+	"github.com/jetstack/cert-manager/pkg/apis/acme/v1beta1"
+)
+
+// Convert_acme_ACMEIssuer_To_v1beta1_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_acme_ACMEIssuer_To_v1beta1_ACMEIssuer(in *acme.ACMEIssuer, out *v1beta1.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_acme_ACMEIssuer_To_v1beta1_ACMEIssuer(in, out, s)
+}
+
+// Convert_v1beta1_ACMEIssuer_To_acme_ACMEIssuer is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1beta1_ACMEIssuer_To_acme_ACMEIssuer(in *v1beta1.ACMEIssuer, out *acme.ACMEIssuer, s conversion.Scope) error {
+	return autoConvert_v1beta1_ACMEIssuer_To_acme_ACMEIssuer(in, out, s)
+}
diff --git a/internal/apis/meta/v1/BUILD.bazel b/internal/apis/meta/v1/BUILD.bazel
index ef3449af0..e9efdf8dd 100644
--- a/internal/apis/meta/v1/BUILD.bazel
+++ b/internal/apis/meta/v1/BUILD.bazel
@@ -3,6 +3,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 go_library(
     name = "go_default_library",
     srcs = [
+        "conversion.go",
         "defaults.go",
         "doc.go",
         "register.go",
diff --git a/internal/apis/meta/v1/conversion.go b/internal/apis/meta/v1/conversion.go
new file mode 100644
index 000000000..d62529760
--- /dev/null
+++ b/internal/apis/meta/v1/conversion.go
@@ -0,0 +1,60 @@
+/*
+Copyright 2021 The cert-manager Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	"k8s.io/apimachinery/pkg/conversion"
+
+	"github.com/jetstack/cert-manager/internal/apis/meta"
+	"github.com/jetstack/cert-manager/pkg/apis/meta/v1"
+)
+
+// Convert_meta_LocalObjectReference_To_v1_LocalObjectReference is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_meta_LocalObjectReference_To_v1_LocalObjectReference(in *meta.LocalObjectReference, out *v1.LocalObjectReference, s conversion.Scope) error {
+	return autoConvert_meta_LocalObjectReference_To_v1_LocalObjectReference(in, out, s)
+}
+
+// Convert_v1_LocalObjectReference_To_meta_LocalObjectReference is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1_LocalObjectReference_To_meta_LocalObjectReference(in *v1.LocalObjectReference, out *meta.LocalObjectReference, s conversion.Scope) error {
+	return autoConvert_v1_LocalObjectReference_To_meta_LocalObjectReference(in, out, s)
+}
+
+// Convert_meta_ObjectReference_To_v1_ObjectReference is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_meta_ObjectReference_To_v1_ObjectReference(in *meta.ObjectReference, out *v1.ObjectReference, s conversion.Scope) error {
+	return autoConvert_meta_ObjectReference_To_v1_ObjectReference(in, out, s)
+}
+
+// Convert_v1_ObjectReference_To_meta_ObjectReference is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1_ObjectReference_To_meta_ObjectReference(in *v1.ObjectReference, out *meta.ObjectReference, s conversion.Scope) error {
+	return autoConvert_v1_ObjectReference_To_meta_ObjectReference(in, out, s)
+}
+
+// Convert_meta_SecretKeySelector_To_v1_SecretKeySelector is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_meta_SecretKeySelector_To_v1_SecretKeySelector(in *meta.SecretKeySelector, out *v1.SecretKeySelector, s conversion.Scope) error {
+	return autoConvert_meta_SecretKeySelector_To_v1_SecretKeySelector(in, out, s)
+}
+
+// Convert_v1_SecretKeySelector_To_meta_SecretKeySelector is explicitly defined to avoid issues in conversion-gen
+// when referencing types in other API groups.
+func Convert_v1_SecretKeySelector_To_meta_SecretKeySelector(in *v1.SecretKeySelector, out *meta.SecretKeySelector, s conversion.Scope) error {
+	return autoConvert_v1_SecretKeySelector_To_meta_SecretKeySelector(in, out, s)
+}