diff --git a/registry/storage/cache/memory/memory.go b/registry/storage/cache/memory/memory.go
index 68a68f08..cf125e18 100644
--- a/registry/storage/cache/memory/memory.go
+++ b/registry/storage/cache/memory/memory.go
@@ -77,37 +77,46 @@ type repositoryScopedInMemoryBlobDescriptorCache struct {
 }
 
 func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
-	if rsimbdcp.repository == nil {
+	rsimbdcp.parent.mu.Lock()
+	repo := rsimbdcp.repository
+	rsimbdcp.parent.mu.Unlock()
+
+	if repo == nil {
 		return distribution.Descriptor{}, distribution.ErrBlobUnknown
 	}
 
-	return rsimbdcp.repository.Stat(ctx, dgst)
+	return repo.Stat(ctx, dgst)
 }
 
 func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) Clear(ctx context.Context, dgst digest.Digest) error {
-	if rsimbdcp.repository == nil {
+	rsimbdcp.parent.mu.Lock()
+	repo := rsimbdcp.repository
+	rsimbdcp.parent.mu.Unlock()
+
+	if repo == nil {
 		return distribution.ErrBlobUnknown
 	}
 
-	return rsimbdcp.repository.Clear(ctx, dgst)
+	return repo.Clear(ctx, dgst)
 }
 
 func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
-	if rsimbdcp.repository == nil {
+	rsimbdcp.parent.mu.Lock()
+	repo := rsimbdcp.repository
+	if repo == nil {
 		// allocate map since we are setting it now.
-		rsimbdcp.parent.mu.Lock()
 		var ok bool
 		// have to read back value since we may have allocated elsewhere.
-		rsimbdcp.repository, ok = rsimbdcp.parent.repositories[rsimbdcp.repo]
+		repo, ok = rsimbdcp.parent.repositories[rsimbdcp.repo]
 		if !ok {
-			rsimbdcp.repository = newMapBlobDescriptorCache()
-			rsimbdcp.parent.repositories[rsimbdcp.repo] = rsimbdcp.repository
+			repo = newMapBlobDescriptorCache()
+			rsimbdcp.parent.repositories[rsimbdcp.repo] = repo
 		}
-
-		rsimbdcp.parent.mu.Unlock()
+		rsimbdcp.repository = repo
 	}
+	rsimbdcp.parent.mu.Unlock()
 
-	if err := rsimbdcp.repository.SetDescriptor(ctx, dgst, desc); err != nil {
+	if err := repo.SetDescriptor(ctx, dgst, desc); err != nil {
 		return err
 	}