diff --git a/registry/server.go b/registry/server.go
index 0059cf07..6d99669a 100644
--- a/registry/server.go
+++ b/registry/server.go
@@ -7,19 +7,28 @@ import (
 	"context"
 	"errors"
 	"log"
+	"math/rand"
 	"net/http"
+	"net/url"
 	"os"
 	"path"
+	"strconv"
 	"time"
 
 	"bllamo.com/build/blob"
 	"bllamo.com/client/ollama"
 	"bllamo.com/oweb"
 	"bllamo.com/registry/apitype"
+	"bllamo.com/utils/upload"
 	"github.com/minio/minio-go/v7"
 	"github.com/minio/minio-go/v7/pkg/credentials"
 )
 
+// Defaults
+const (
+	DefaultUploadChunkSize = 50 * 1024 * 1024
+)
+
 // TODO(bmizerany): move all env things to package envkobs?
 var defaultLibrary = cmp.Or(os.Getenv("OLLAMA_REGISTRY"), "registry.ollama.ai/library")
 
@@ -28,7 +37,8 @@ func DefaultLibrary() string {
 }
 
 type Server struct {
-	minioClient *minio.Client
+	UploadChunkSize int64 // default is DefaultUploadChunkSize
+	minioClient     *minio.Client
 }
 
 func New(mc *minio.Client) *Server {
@@ -77,7 +87,6 @@ func (s *Server) handlePush(w http.ResponseWriter, r *http.Request) error {
 	}
 
 	// TODO(bmizerany): parallelize
-	const chunkSizeTODO = 50 * 1024 * 1024
 	var requirements []apitype.Requirement
 	for _, l := range m.Layers {
 		if l.Size == 0 {
@@ -91,21 +100,29 @@ func (s *Server) handlePush(w http.ResponseWriter, r *http.Request) error {
 			return err
 		}
 		if !pushed {
-			const expires = 15 * time.Minute
-			key := path.Join("blobs", l.Digest)
-			signedURL, err := s.mc().PresignedPutObject(r.Context(), "test", key, expires)
-			if err != nil {
-				return err
+			uploadID := generateUploadID()
+			for n, c := range upload.Chunks(l.Size, cmp.Or(s.UploadChunkSize, DefaultUploadChunkSize)) {
+				const expires = 15 * time.Minute
+
+				key := path.Join("blobs", l.Digest)
+				signedURL, err := s.mc().Presign(r.Context(), "PUT", "test", key, expires, url.Values{
+					"UploadId":      []string{uploadID},
+					"PartNumber":    []string{strconv.Itoa(n)},
+					"ContentLength": []string{strconv.FormatInt(c.Size, 10)},
+				})
+				if err != nil {
+					return err
+				}
+
+				requirements = append(requirements, apitype.Requirement{
+					Digest: l.Digest,
+					Offset: c.Offset,
+					Size:   c.Size,
+
+					// TODO(bmizerany): use signed+temp urls
+					URL: signedURL.String(),
+				})
 			}
-
-			size := min(l.Size, chunkSizeTODO)
-			requirements = append(requirements, apitype.Requirement{
-				Digest: l.Digest,
-				Size:   size,
-
-				// TODO(bmizerany): use signed+temp urls
-				URL: signedURL.String(),
-			})
 		}
 	}
 
@@ -158,3 +175,12 @@ func (s *Server) mc() *minio.Client {
 	}
 	return mc
 }
+
+func generateUploadID() string {
+	const hex = "0123456789abcdef"
+	b := make([]byte, 32)
+	for i := range b {
+		b[i] = hex[rand.Intn(len(hex))]
+	}
+	return string(b)
+}