diff --git a/go/ssa/interp/reflect.go b/go/ssa/interp/reflect.go
index f5bf3d03..468771b4 100644
--- a/go/ssa/interp/reflect.go
+++ b/go/ssa/interp/reflect.go
@@ -511,7 +511,7 @@ func newMethod(pkg *ssa.Package, recvType types.Type, name string) *ssa.Function
 	// that is needed is the "pointerness" of Recv.Type, and for
 	// now, we'll set it to always be false since we're only
 	// concerned with rtype.  Encapsulate this better.
-	sig := types.NewSignature(nil, types.NewVar(token.NoPos, nil, "recv", recvType), nil, nil, false)
+	sig := types.NewSignature(types.NewVar(token.NoPos, nil, "recv", recvType), nil, nil, false)
 	fn := pkg.Prog.NewFunction(name, sig, "fake reflect method")
 	fn.Pkg = pkg
 	return fn
diff --git a/go/ssa/testmain.go b/go/ssa/testmain.go
index 7935f4ef..a7b1242a 100644
--- a/go/ssa/testmain.go
+++ b/go/ssa/testmain.go
@@ -31,9 +31,9 @@ func FindTests(pkgs []*Package) (testpkgs []*Package, tests, benchmarks, example
 
 	// The first two of these may be nil: if the program doesn't import "testing",
 	// it can't contain any tests, but it may yet contain Examples.
-	var testSig *types.Signature                                   // func(*testing.T)
-	var benchmarkSig *types.Signature                              // func(*testing.B)
-	var exampleSig = types.NewSignature(nil, nil, nil, nil, false) // func()
+	var testSig *types.Signature                              // func(*testing.T)
+	var benchmarkSig *types.Signature                         // func(*testing.B)
+	var exampleSig = types.NewSignature(nil, nil, nil, false) // func()
 
 	// Obtain the types from the parameters of testing.Main().
 	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
diff --git a/go/ssa/util.go b/go/ssa/util.go
index 10ebb8cd..4f9d43da 100644
--- a/go/ssa/util.go
+++ b/go/ssa/util.go
@@ -114,6 +114,6 @@ func makeLen(T types.Type) *Builtin {
 	lenParams := types.NewTuple(anonVar(T))
 	return &Builtin{
 		name: "len",
-		sig:  types.NewSignature(nil, nil, lenParams, lenResults, false),
+		sig:  types.NewSignature(nil, lenParams, lenResults, false),
 	}
 }
diff --git a/go/ssa/wrappers.go b/go/ssa/wrappers.go
index 3c7e7f04..ff1eac51 100644
--- a/go/ssa/wrappers.go
+++ b/go/ssa/wrappers.go
@@ -89,7 +89,7 @@ func makeWrapper(prog *Program, sel *types.Selection) *Function {
 			var c Call
 			c.Call.Value = &Builtin{
 				name: "ssa:wrapnilchk",
-				sig: types.NewSignature(nil, nil,
+				sig: types.NewSignature(nil,
 					types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)),
 					types.NewTuple(anonVar(sel.Recv())), false),
 			}
@@ -281,7 +281,7 @@ func makeThunk(prog *Program, sel *types.Selection) *Function {
 }
 
 func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
-	return types.NewSignature(nil, recv, s.Params(), s.Results(), s.Variadic())
+	return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic())
 }
 
 // selectionKey is like types.Selection but a usable map key.