diff --git a/cmd/migrate/migration/init.go b/cmd/migrate/migration/init.go
index 08e61160..669bec65 100644
--- a/cmd/migrate/migration/init.go
+++ b/cmd/migrate/migration/init.go
@@ -3,7 +3,6 @@ package migration
 import (
 	"fmt"
 	"log"
-	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -363,7 +362,10 @@ func (e *Migration) run(appCode string) {
 // from the empty app code, which selects the framework's own migrations.
 const allApps = "\x00all"
 
+// GetFilename derives a migration's version from its file name. The rule
+// lives in contract/migration, because an application registering through
+// that package names its files by the same convention and must land on the
+// same version string; a second copy here is a second thing to keep in step.
 func GetFilename(s string) string {
-	s = filepath.Base(s)
-	return s[:13]
+	return contractmigration.GetFilename(s)
 }
diff --git a/cmd/migrate/migration/init_test.go b/cmd/migrate/migration/init_test.go
index c4c8db6f..13d8c6a6 100644
--- a/cmd/migrate/migration/init_test.go
+++ b/cmd/migrate/migration/init_test.go
@@ -561,3 +561,22 @@ func TestMergedEntriesHostRegistrationWinsOnKeyCollision(t *testing.T) {
 		t.Error("contract registration ran; host registration should have won the collision")
 	}
 }
+
+// GetFilename must stay the same rule the contract package applies, since an
+// application registering through contract/migration names its files by that
+// convention and has to land on the same version string. Pinning the reject
+// case is what catches a re-divergence: a local copy that only sliced would
+// return "add_orders.go" here and register a migration under a key that never
+// matches anything.
+func TestGetFilenameDelegatesToTheContractRule(t *testing.T) {
+	if got := GetFilename("version/1786700001000_demo_menu.go"); got != "1786700001000" {
+		t.Fatalf("GetFilename = %q, want %q", got, "1786700001000")
+	}
+
+	defer func() {
+		if recover() == nil {
+			t.Fatal("a file name carrying no version did not panic")
+		}
+	}()
+	GetFilename("version/add_orders.go")
+}