diff --git a/cmd/cloner/cloner.go b/cmd/cloner/cloner.go
index 123529f95..f24632eee 100644
--- a/cmd/cloner/cloner.go
+++ b/cmd/cloner/cloner.go
@@ -218,7 +218,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
 	writef("return dst")
 	fmt.Fprintf(buf, "}\n\n")
 
-	buf.Write(codegen.AssertStructUnchanged(t, name, "Clone", thisPkg, imports))
+	buf.Write(codegen.AssertStructUnchanged(t, thisPkg, name, "Clone", imports))
 }
 
 func hasBasicUnderlying(typ types.Type) bool {
diff --git a/util/codegen/codegen.go b/util/codegen/codegen.go
index 2df6c9b25..4265806ee 100644
--- a/util/codegen/codegen.go
+++ b/util/codegen/codegen.go
@@ -72,12 +72,12 @@ func NamedTypes(pkg *packages.Package) map[string]*types.Named {
 }
 
 // AssertStructUnchanged generates code that asserts at compile time that type t is unchanged.
+// thisPkg is the package containing t.
 // tname is the named type corresponding to t.
 // ctx is a single-word context for this assertion, such as "Clone".
-// thisPkg is the package containing t.
 // If non-nil, AssertStructUnchanged will add elements to imports
 // for each package path that the caller must import for the returned code to compile.
-func AssertStructUnchanged(t *types.Struct, tname, ctx string, thisPkg *types.Package, imports map[string]struct{}) []byte {
+func AssertStructUnchanged(t *types.Struct, thisPkg *types.Package, tname, ctx string, imports map[string]struct{}) []byte {
 	buf := new(bytes.Buffer)
 	w := func(format string, args ...interface{}) {
 		fmt.Fprintf(buf, format+"\n", args...)