diff --git a/pkg/client/apiutil/apiutil_suite_test.go b/pkg/client/apiutil/apiutil_suite_test.go
index 4a4d7905a5..56ab65bfab 100644
--- a/pkg/client/apiutil/apiutil_suite_test.go
+++ b/pkg/client/apiutil/apiutil_suite_test.go
@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package apiutil_test
+package apiutil
 
 import (
 	"testing"
diff --git a/pkg/client/apiutil/dynamicrestmapper.go b/pkg/client/apiutil/dynamicrestmapper.go
index 5e9a7b5f53..4dce3c7131 100644
--- a/pkg/client/apiutil/dynamicrestmapper.go
+++ b/pkg/client/apiutil/dynamicrestmapper.go
@@ -1,24 +1,9 @@
-/*
-Copyright 2019 The Kubernetes 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 apiutil
 
 import (
 	"errors"
 	"sync"
+	"sync/atomic"
 
 	"golang.org/x/time/rate"
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -38,7 +23,8 @@ type dynamicRESTMapper struct {
 
 	lazy bool
 	// Used for lazy init.
-	initOnce sync.Once
+	inited  uint32
+	initMtx sync.Mutex
 }
 
 // DynamicRESTMapperOption is a functional option on the dynamicRESTMapper
@@ -125,11 +111,18 @@ func (drm *dynamicRESTMapper) setStaticMapper() error {
 
 // init initializes drm only once if drm is lazy.
 func (drm *dynamicRESTMapper) init() (err error) {
-	drm.initOnce.Do(func() {
-		if drm.lazy {
-			err = drm.setStaticMapper()
+	// skip init if drm is not lazy or has initialized
+	if !drm.lazy || atomic.LoadUint32(&drm.inited) != 0 {
+		return nil
+	}
+
+	drm.initMtx.Lock()
+	defer drm.initMtx.Unlock()
+	if drm.inited == 0 {
+		if err = drm.setStaticMapper(); err == nil {
+			atomic.StoreUint32(&drm.inited, 1)
 		}
-	})
+	}
 	return err
 }
 
diff --git a/pkg/client/apiutil/dynamicrestmapper_test.go b/pkg/client/apiutil/dynamicrestmapper_test.go
index ff292d6182..6b88a3aa5f 100644
--- a/pkg/client/apiutil/dynamicrestmapper_test.go
+++ b/pkg/client/apiutil/dynamicrestmapper_test.go
@@ -1,6 +1,23 @@
-package apiutil_test
+/*
+Copyright 2021 The Kubernetes 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 apiutil
 
 import (
+	"fmt"
 	"time"
 
 	. "github.com/onsi/ginkgo"
@@ -10,8 +27,6 @@ import (
 	"golang.org/x/time/rate"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-
-	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 )
 
 var (
@@ -36,7 +51,7 @@ var _ = Describe("Dynamic REST Mapper", func() {
 		}
 
 		lim = rate.NewLimiter(rate.Limit(5), 5)
-		mapper, err = apiutil.NewDynamicRESTMapper(cfg, apiutil.WithLimiter(lim), apiutil.WithCustomMapper(func() (meta.RESTMapper, error) {
+		mapper, err = NewDynamicRESTMapper(cfg, WithLimiter(lim), WithCustomMapper(func() (meta.RESTMapper, error) {
 			baseMapper := meta.NewDefaultRESTMapper(nil)
 			addToMapper(baseMapper)
 
@@ -130,11 +145,28 @@ var _ = Describe("Dynamic REST Mapper", func() {
 			By("ensuring that it was only refreshed once")
 			Expect(count).To(Equal(1))
 		})
-	}
 
-	PIt("should lazily initialize if the lazy option is used", func() {
-
-	})
+		It("should lazily initialize if the lazy option is used", func() {
+			var err error
+			var failedOnce bool
+			mockErr := fmt.Errorf("mock failed once")
+			mapper, err = NewDynamicRESTMapper(cfg, WithLazyDiscovery, WithCustomMapper(func() (meta.RESTMapper, error) {
+				// Make newMapper fail once
+				if !failedOnce {
+					failedOnce = true
+					return nil, mockErr
+				}
+				baseMapper := meta.NewDefaultRESTMapper(nil)
+				addToMapper(baseMapper)
+				return baseMapper, nil
+			}))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(mapper.(*dynamicRESTMapper).staticMapper).To(BeNil())
+
+			Expect(callWithTarget()).To(MatchError(mockErr))
+			Expect(callWithTarget()).To(Succeed())
+		})
+	}
 
 	Describe("KindFor", func() {
 		mapperTest(func() error {