diff --git a/cmd/rehash.go b/cmd/rehash.go
new file mode 100644
index 0000000..0019d70
--- /dev/null
+++ b/cmd/rehash.go
@@ -0,0 +1,93 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/packwiz/packwiz/core"
+	"github.com/spf13/cobra"
+	"golang.org/x/exp/slices"
+)
+
+// rehashCmd represents the rehash command
+var rehashCmd = &cobra.Command{
+	Use:   "rehash",
+	Short: "Migrate all hashes to a specific function",
+	Args:  cobra.ExactArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+
+		// Load pack
+		pack, err := core.LoadPack()
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+
+		// Load index
+		index, err := pack.LoadIndex()
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+
+		// Load mods
+		mods, err := index.LoadAllMods()
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+
+		if !slices.Contains([]string{"sha1", "sha512", "sha256"}, args[0]) {
+			fmt.Printf("Hash format '%s' is not supported\n", args[0])
+			os.Exit(1)
+		}
+
+		session, err := core.CreateDownloadSession(mods, []string{args[0]})
+		if err != nil {
+			fmt.Printf("Error retrieving external files: %v\n", err)
+			os.Exit(1)
+		}
+		for dl := range session.StartDownloads() {
+			if dl.Error != nil {
+				fmt.Printf("Error retrieving %s: %v\n", dl.Mod.Name, dl.Error)
+			} else {
+				dl.Mod.Download.HashFormat = args[0]
+				dl.Mod.Download.Hash = dl.Hashes[args[0]]
+				_, _, err := dl.Mod.Write()
+				if err != nil {
+					fmt.Printf("Error saving mod %s: %v\n", dl.Mod.Name, err)
+					os.Exit(1)
+				}
+			}
+			// TODO pass the hash to index instead of recomputing from scratch
+		}
+
+		err = index.Refresh()
+		if err != nil {
+			fmt.Printf("Error refreshing index: %v\n", err)
+			os.Exit(1)
+		}
+
+		err = index.Write()
+		if err != nil {
+			fmt.Printf("Error writing index: %v\n", err)
+			os.Exit(1)
+		}
+
+		err = pack.UpdateIndexHash()
+		if err != nil {
+			fmt.Printf("Error updating index hash: %v\n", err)
+			os.Exit(1)
+		}
+
+		err = pack.Write()
+		if err != nil {
+			fmt.Printf("Error writing pack: %v\n", err)
+			os.Exit(1)
+		}
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(rehashCmd)
+}
diff --git a/modrinth/modrinth.go b/modrinth/modrinth.go
index fa38bbc..71fb7b3 100644
--- a/modrinth/modrinth.go
+++ b/modrinth/modrinth.go
@@ -361,12 +361,9 @@ func shouldDownloadOnSide(side string) bool {
 }
 
 func getBestHash(v *modrinthApi.File) (string, string) {
-	// Try preferred hashes first; SHA1 is first as it is required for Modrinth pack exporting
-	val, exists := v.Hashes["sha1"]
-	if exists {
-		return "sha1", val
-	}
-	val, exists = v.Hashes["sha512"]
+	// Try preferred hashes first; SHA1 is required for Modrinth pack exporting, but
+	// so is SHA512, so we can't win with the current one-hash format
+	val, exists := v.Hashes["sha512"]
 	if exists {
 		return "sha512", val
 	}
@@ -374,6 +371,10 @@ func getBestHash(v *modrinthApi.File) (string, string) {
 	if exists {
 		return "sha256", val
 	}
+	val, exists = v.Hashes["sha1"]
+	if exists {
+		return "sha1", val
+	}
 	val, exists = v.Hashes["murmur2"] // (not defined in Modrinth pack spec, use with caution)
 	if exists {
 		return "murmur2", val