diff --git a/build/context.go b/build/context.go
index 38ad6f8..84353ee 100644
--- a/build/context.go
+++ b/build/context.go
@@ -6,9 +6,11 @@ import (
 	"github.com/mmcloughlin/avo"
 	"github.com/mmcloughlin/avo/gotypes"
 	"github.com/mmcloughlin/avo/reg"
+	"golang.org/x/tools/go/packages"
 )
 
 type Context struct {
+	pkg      *packages.Package
 	file     *avo.File
 	function *avo.Function
 	errs     []error
@@ -22,6 +24,25 @@ func NewContext() *Context {
 	}
 }
 
+func (c *Context) Package(path string) {
+	cfg := &packages.Config{
+		Mode: packages.LoadTypes,
+	}
+	pkgs, err := packages.Load(cfg, path)
+	if err != nil {
+		c.AddError(err)
+		return
+	}
+	pkg := pkgs[0]
+	if len(pkg.Errors) > 0 {
+		for _, err := range pkg.Errors {
+			c.AddError(err)
+		}
+		return
+	}
+	c.pkg = pkg
+}
+
 func (c *Context) Function(name string) {
 	c.function = avo.NewFunction(name)
 	c.file.Functions = append(c.file.Functions, c.function)
@@ -32,7 +53,7 @@ func (c *Context) Signature(s *gotypes.Signature) {
 }
 
 func (c *Context) SignatureExpr(expr string) {
-	s, err := gotypes.ParseSignature(expr)
+	s, err := gotypes.ParseSignatureInPackage(c.pkg.Types, expr)
 	if err != nil {
 		c.AddError(err)
 		return
diff --git a/build/global.go b/build/global.go
index 7307328..f89fe28 100644
--- a/build/global.go
+++ b/build/global.go
@@ -14,6 +14,8 @@ import (
 // ctx provides a global build context.
 var ctx = NewContext()
 
+func Package(path string) { ctx.Package(path) }
+
 func TEXT(name, signature string) {
 	ctx.Function(name)
 	ctx.SignatureExpr(signature)
diff --git a/examples/components/asm.go b/examples/components/asm.go
new file mode 100644
index 0000000..5723c3f
--- /dev/null
+++ b/examples/components/asm.go
@@ -0,0 +1,21 @@
+// +build ignore
+
+package main
+
+import (
+	. "github.com/mmcloughlin/avo/build"
+)
+
+func main() {
+	Package("github.com/mmcloughlin/avo/examples/components")
+
+	// Add confirms that we correctly deduce the packing of Struct.
+	TEXT("Add", "func(x uint64, s Struct, y uint64) uint64")
+	x := Load(Param("x"), GP64v())
+	y := Load(Param("y"), GP64v())
+	ADDQ(x, y)
+	Store(y, ReturnIndex(0))
+	RET()
+
+	Generate()
+}
diff --git a/examples/components/components.go b/examples/components/components.go
new file mode 100644
index 0000000..83a72d4
--- /dev/null
+++ b/examples/components/components.go
@@ -0,0 +1,20 @@
+package components
+
+type Struct struct {
+	Byte       byte
+	Uint32     uint32
+	Uint64     uint64
+	Float32    float32
+	Float64    float64
+	String     string
+	Slice      []Sub
+	Array      [5]Sub
+	Complex64  complex64
+	Complex128 complex128
+}
+
+type Sub struct {
+	A uint64
+	B [3]byte
+	C uint16
+}
diff --git a/examples/components/components.s b/examples/components/components.s
new file mode 100644
index 0000000..d74bbd4
--- /dev/null
+++ b/examples/components/components.s
@@ -0,0 +1,10 @@
+
+#include "textflag.h"
+
+// func Add(x uint64, s Struct, y uint64) uint64
+TEXT ·Add(SB),0,$0-200
+	MOVQ	x(FP), AX
+	MOVQ	y+184(FP), CX
+	ADDQ	AX, CX
+	MOVQ	CX, ret+192(FP)
+	RET	
diff --git a/examples/components/components_test.go b/examples/components/components_test.go
new file mode 100644
index 0000000..0cdcca0
--- /dev/null
+++ b/examples/components/components_test.go
@@ -0,0 +1,15 @@
+package components
+
+import (
+	"testing"
+	"testing/quick"
+)
+
+//go:generate go run asm.go -out components.s -stubs stub.go
+
+func TestAdd(t *testing.T) {
+	expect := func(x uint64, s Struct, y uint64) uint64 { return x + y }
+	if err := quick.CheckEqual(Add, expect, nil); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/examples/components/stub.go b/examples/components/stub.go
new file mode 100644
index 0000000..680d107
--- /dev/null
+++ b/examples/components/stub.go
@@ -0,0 +1,3 @@
+package components
+
+func Add(x uint64, s Struct, y uint64) uint64
diff --git a/gotypes/components.go b/gotypes/components.go
index 25c394f..dcdeacf 100644
--- a/gotypes/components.go
+++ b/gotypes/components.go
@@ -56,12 +56,13 @@ func NewComponentFromVar(v *types.Var, offset int) Component {
 }
 
 func (c *component) Resolve() (*Basic, error) {
-	if !isprimitive(c.typ) {
+	b := toprimitive(c.typ)
+	if b == nil {
 		return nil, errors.New("component is not primitive")
 	}
 	return &Basic{
 		Addr: operand.NewParamAddr(c.name, c.offset),
-		Type: c.typ.(*types.Basic),
+		Type: b,
 	}, nil
 }
 
@@ -181,8 +182,17 @@ func complextofloat(t types.Type) types.Type {
 	panic("bad")
 }
 
-// isprimitive returns true if the type cannot be broken into components.
-func isprimitive(t types.Type) bool {
-	b, ok := t.(*types.Basic)
-	return ok && (b.Info()&(types.IsString|types.IsComplex)) == 0
+// toprimitive determines whether t is primitive (cannot be reduced into
+// components). If it is, it returns the basic type for t, otherwise returns
+// nil.
+func toprimitive(t types.Type) *types.Basic {
+	switch b := t.(type) {
+	case *types.Basic:
+		if (b.Info() & (types.IsString | types.IsComplex)) == 0 {
+			return b
+		}
+	case *types.Pointer:
+		return types.Typ[types.Uintptr]
+	}
+	return nil
 }
diff --git a/gotypes/components_test.go b/gotypes/components_test.go
new file mode 100644
index 0000000..4d021b9
--- /dev/null
+++ b/gotypes/components_test.go
@@ -0,0 +1,40 @@
+package gotypes
+
+import (
+	"go/types"
+	"testing"
+)
+
+func TestBasicKindsArePrimitive(t *testing.T) {
+	kinds := []types.BasicKind{
+		types.Bool,
+		types.Int,
+		types.Int8,
+		types.Int16,
+		types.Int32,
+		types.Int64,
+		types.Uint,
+		types.Uint8,
+		types.Uint16,
+		types.Uint32,
+		types.Uint64,
+		types.Uintptr,
+		types.Float32,
+		types.Float64,
+	}
+	for _, k := range kinds {
+		AssertPrimitive(t, types.Typ[k])
+	}
+}
+
+func TestPointersArePrimitive(t *testing.T) {
+	typ := types.NewPointer(types.Typ[types.Uint32])
+	AssertPrimitive(t, typ)
+}
+
+func AssertPrimitive(t *testing.T, typ types.Type) {
+	c := NewComponent("primitive", typ, 0)
+	if _, err := c.Resolve(); err != nil {
+		t.Errorf("expected type %s to be primitive: got error '%s'", typ, err)
+	}
+}
diff --git a/gotypes/signature.go b/gotypes/signature.go
index f6052ed..692b205 100644
--- a/gotypes/signature.go
+++ b/gotypes/signature.go
@@ -10,13 +10,15 @@ import (
 )
 
 type Signature struct {
+	pkg     *types.Package
 	sig     *types.Signature
 	params  *Tuple
 	results *Tuple
 }
 
-func NewSignature(sig *types.Signature) *Signature {
+func NewSignature(pkg *types.Package, sig *types.Signature) *Signature {
 	s := &Signature{
+		pkg: pkg,
 		sig: sig,
 	}
 	s.init()
@@ -24,11 +26,15 @@ func NewSignature(sig *types.Signature) *Signature {
 }
 
 func NewSignatureVoid() *Signature {
-	return NewSignature(types.NewSignature(nil, nil, nil, false))
+	return NewSignature(nil, types.NewSignature(nil, nil, nil, false))
 }
 
 func ParseSignature(expr string) (*Signature, error) {
-	tv, err := types.Eval(token.NewFileSet(), nil, token.NoPos, expr)
+	return ParseSignatureInPackage(nil, expr)
+}
+
+func ParseSignatureInPackage(pkg *types.Package, expr string) (*Signature, error) {
+	tv, err := types.Eval(token.NewFileSet(), pkg, token.NoPos, expr)
 	if err != nil {
 		return nil, err
 	}
@@ -39,7 +45,7 @@ func ParseSignature(expr string) (*Signature, error) {
 	if !ok {
 		return nil, errors.New("provided type is not a function signature")
 	}
-	return NewSignature(s), nil
+	return NewSignature(pkg, s), nil
 }
 
 func (s *Signature) Params() *Tuple { return s.params }
@@ -50,7 +56,7 @@ func (s *Signature) Bytes() int { return s.Params().Bytes() + s.Results().Bytes(
 
 func (s *Signature) String() string {
 	var buf bytes.Buffer
-	types.WriteSignature(&buf, s.sig, nil)
+	types.WriteSignature(&buf, s.sig, types.RelativeTo(s.pkg))
 	return buf.String()
 }