diff --git a/cl/cltest/cltest.go b/cl/cltest/cltest.go
index 6b1208c1..fbe500be 100644
--- a/cl/cltest/cltest.go
+++ b/cl/cltest/cltest.go
@@ -143,7 +143,7 @@ func TestCompileEx(t *testing.T, src any, fname, expected string) {
 	foo.WriteTo(os.Stderr)
 	prog := ssatest.NewProgramEx(t, nil, imp)
 
-	ret, err := cl.NewPackage(prog, foo, files)
+	ret, err := cl.NewPackage(prog, foo, nil, files)
 	if err != nil {
 		t.Fatal("cl.NewPackage failed:", err)
 	}
diff --git a/cl/compile.go b/cl/compile.go
index 4239f465..06ca17f5 100644
--- a/cl/compile.go
+++ b/cl/compile.go
@@ -953,7 +953,7 @@ func (p *context) compileValues(b llssa.Builder, vals []ssa.Value, hasVArg int)
 // -----------------------------------------------------------------------------
 
 // NewPackage compiles a Go package to LLVM IR package.
-func NewPackage(prog llssa.Program, pkg *ssa.Package, files []*ast.File) (ret llssa.Package, err error) {
+func NewPackage(prog llssa.Program, pkg, alt *ssa.Package, files []*ast.File) (ret llssa.Package, err error) {
 	type namedMember struct {
 		name string
 		val  ssa.Member
diff --git a/internal/build/build.go b/internal/build/build.go
index 82e1bfd8..eacb4277 100644
--- a/internal/build/build.go
+++ b/internal/build/build.go
@@ -365,7 +365,12 @@ func buildPkg(prog llssa.Program, aPkg *aPackage, mode Mode, verbose bool) {
 		pkg.ExportFile = ""
 		return
 	}
-	ret, err := cl.NewPackage(prog, aPkg.SSA, pkg.Syntax)
+	syntax := pkg.Syntax
+	if altPkg := aPkg.AltPkg; altPkg != nil {
+		// TODO: merge pkg.Types
+		syntax = append(syntax, altPkg.Syntax...)
+	}
+	ret, err := cl.NewPackage(prog, aPkg.SSA, aPkg.AltSSA, syntax)
 	check(err)
 	if needLLFile(mode) {
 		pkg.ExportFile += ".ll"
diff --git a/internal/llgen/llgen.go b/internal/llgen/llgen.go
index 2a62b637..d50dfe56 100644
--- a/internal/llgen/llgen.go
+++ b/internal/llgen/llgen.go
@@ -80,7 +80,7 @@ func Gen(pkgPath, inFile string, src any) string {
 		return ret
 	})
 
-	ret, err := cl.NewPackage(prog, ssaPkg, files)
+	ret, err := cl.NewPackage(prog, ssaPkg, nil, files)
 	check(err)
 
 	if prog.NeedPyInit { // call PyInit if needed
diff --git a/internal/llgen/llgenf.go b/internal/llgen/llgenf.go
index 843c245a..36adf090 100644
--- a/internal/llgen/llgenf.go
+++ b/internal/llgen/llgenf.go
@@ -80,7 +80,7 @@ func GenFrom(fileOrPkg string) string {
 		ssaPkg.WriteTo(os.Stderr)
 	}
 
-	ret, err := cl.NewPackage(prog, ssaPkg, pkg.Syntax)
+	ret, err := cl.NewPackage(prog, ssaPkg, nil, pkg.Syntax)
 	check(err)
 
 	if prog.NeedPyInit { // call PyInit if needed