diff --git a/internal/runtime/type.go b/internal/runtime/type.go
index 36ce1a0f..8e8b4332 100644
--- a/internal/runtime/type.go
+++ b/internal/runtime/type.go
@@ -12,11 +12,9 @@ import (
 
 type _type = abi.Type
 
-type interfacetype = abi.InterfaceType
-
+/*
 type maptype = abi.MapType
 
-/*
 type arraytype = abi.ArrayType
 
 type chantype = abi.ChanType
diff --git a/internal/runtime/z_face.go b/internal/runtime/z_face.go
index 28409f1e..01907b0a 100644
--- a/internal/runtime/z_face.go
+++ b/internal/runtime/z_face.go
@@ -21,6 +21,8 @@ type iface struct {
 	data unsafe.Pointer
 }
 
+type interfacetype = abi.InterfaceType
+
 // layout of Itab known to compilers
 // allocated in non-garbage-collected memory
 // Needs to be in sync with
@@ -126,12 +128,10 @@ func Named(pkgPath, name Name, underlying *Type, methods []abi.Method) *Type {
 	}
 
 	uncommon := (*abi.UncommonType)(c.Advance(ptr, int(typeHdrSize)))
-	*uncommon = abi.UncommonType{
-		PkgPath_: pkgPath,
-		Mcount:   uint16(n),
-		Xcount:   uint16(xcount),
-		Moff:     uint32(uncommonTypeHdrSize),
-	}
+	uncommon.PkgPath_ = pkgPath
+	uncommon.Mcount = uint16(n)
+	uncommon.Xcount = uint16(xcount)
+	uncommon.Moff = uint32(uncommonTypeHdrSize)
 
 	data := (*abi.Method)(c.Advance(ptr, int(typeHdrSize+uncommonTypeHdrSize)))
 	copy(unsafe.Slice(data, n), methods)
@@ -139,18 +139,14 @@ func Named(pkgPath, name Name, underlying *Type, methods []abi.Method) *Type {
 }
 
 // Interface returns an interface type.
-func Interface(pkgPath string, methods []abi.Imethod) *Type {
-	var npkg abi.Name
-	if len(pkgPath) > 0 {
-		npkg = abi.NewName(pkgPath, "", false, false)
-	}
+func Interface(pkgPath Name, methods []abi.Imethod) *Type {
 	ret := &abi.InterfaceType{
 		Type: Type{
 			Size_: unsafe.Sizeof(eface{}),
 			Hash:  uint32(abi.Interface), // TODO(xsw): hash
 			Kind_: uint8(abi.Interface),
 		},
-		PkgPath: npkg,
+		PkgPath: pkgPath,
 		Methods: methods,
 	}
 	return &ret.Type
diff --git a/ssa/expr.go b/ssa/expr.go
index 0258755c..9ff69d84 100644
--- a/ssa/expr.go
+++ b/ssa/expr.go
@@ -221,6 +221,11 @@ func (b Builder) Str(v string) (ret Expr) {
 	return Expr{aggregateValue(b.impl, prog.rtString(), data, size), prog.String()}
 }
 
+func (b Builder) pkgName(pkgPath string) Expr {
+	// TODO(xsw): use a global cache
+	return b.Call(b.Pkg.rtFunc("NewPkgName"), b.Str(pkgPath))
+}
+
 // unsafeString(data *byte, size int) string
 func (b Builder) unsafeString(data, size llvm.Value) Expr {
 	prog := b.Prog
diff --git a/ssa/interface.go b/ssa/interface.go
index 6d33fc44..b1ab1535 100644
--- a/ssa/interface.go
+++ b/ssa/interface.go
@@ -84,7 +84,7 @@ func (b Builder) abiStructOf(t *types.Struct) Expr {
 		off := uintptr(prog.OffsetOf(typ, i))
 		flds[i] = b.structField(sfAbi, prog, f, off, t.Tag(i))
 	}
-	pkgPath := b.Str(pkg.Path())
+	pkgPath := b.pkgName(pkg.Path())
 	params := strucAbi.raw.Type.(*types.Signature).Params()
 	tSlice := prog.rawType(params.At(params.Len() - 1).Type().(*types.Slice))
 	fldSlice := b.SliceLit(tSlice, flds...)