diff --git a/bind/gen.go b/bind/gen.go
index 2ad555d..b03277f 100644
--- a/bind/gen.go
+++ b/bind/gen.go
@@ -234,6 +234,52 @@ func (g *generator) validPkg(pkg *types.Package) bool {
 	return false
 }
 
+// isSigSupported returns whether the generators can handle a given
+// function signature
+func (g *generator) isSigSupported(t types.Type) bool {
+	sig := t.(*types.Signature)
+	params := sig.Params()
+	for i := 0; i < params.Len(); i++ {
+		if !g.isSupported(params.At(i).Type()) {
+			return false
+		}
+	}
+	res := sig.Results()
+	for i := 0; i < res.Len(); i++ {
+		if !g.isSupported(res.At(i).Type()) {
+			return false
+		}
+	}
+	return true
+}
+
+// isSupported returns whether the generators can handle the type.
+func (g *generator) isSupported(t types.Type) bool {
+	if isErrorType(t) {
+		return true
+	}
+	switch t := t.(type) {
+	case *types.Basic:
+		return true
+	case *types.Slice:
+		switch e := t.Elem().(type) {
+		case *types.Basic:
+			return e.Kind() == types.Uint8
+		}
+	case *types.Pointer:
+		switch t := t.Elem().(type) {
+		case *types.Named:
+			return g.validPkg(t.Obj().Pkg())
+		}
+	case *types.Named:
+		switch t.Underlying().(type) {
+		case *types.Interface, *types.Pointer:
+			return g.validPkg(t.Obj().Pkg())
+		}
+	}
+	return false
+}
+
 var paramRE = regexp.MustCompile(`^p[0-9]*$`)
 
 // paramName replaces incompatible name with a p0-pN name.
diff --git a/bind/gengo.go b/bind/gengo.go
index 6fb839b..654d5c1 100644
--- a/bind/gengo.go
+++ b/bind/gengo.go
@@ -180,7 +180,7 @@ func (g *goGen) genFuncSignature(o *types.Func, objName string) {
 }
 
 func (g *goGen) genFunc(o *types.Func) {
-	if !isSigSupported(o.Type()) {
+	if !g.isSigSupported(o.Type()) {
 		g.Printf("// skipped function %s with unsupported parameter or result types\n", o.Name())
 		return
 	}
@@ -196,7 +196,7 @@ func (g *goGen) genStruct(obj *types.TypeName, T *types.Struct) {
 	methods := exportedMethodSet(types.NewPointer(obj.Type()))
 
 	for _, f := range fields {
-		if t := f.Type(); !isSupported(t) {
+		if t := f.Type(); !g.isSupported(t) {
 			g.Printf("// skipped field %s.%s with unsupported type: %T\n\n", obj.Name(), f.Name(), t)
 			continue
 		}
@@ -221,7 +221,7 @@ func (g *goGen) genStruct(obj *types.TypeName, T *types.Struct) {
 	}
 
 	for _, m := range methods {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -236,7 +236,7 @@ func (g *goGen) genStruct(obj *types.TypeName, T *types.Struct) {
 }
 
 func (g *goGen) genVar(o *types.Var) {
-	if t := o.Type(); !isSupported(t) {
+	if t := o.Type(); !g.isSupported(t) {
 		g.Printf("// skipped variable %s with unsupported type %T\n\n", o.Name(), t)
 		return
 	}
@@ -273,7 +273,7 @@ func (g *goGen) genInterface(obj *types.TypeName) {
 
 	// Define the entry points.
 	for _, m := range summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -298,7 +298,7 @@ func (g *goGen) genInterface(obj *types.TypeName) {
 	g.Printf("func (p *proxy%s_%s) Bind_proxy_refnum__() int32 { return p.Bind_Num }\n\n", g.pkgPrefix, obj.Name())
 
 	for _, m := range summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or result types\n", obj.Name(), m.Name())
 			continue
 		}
diff --git a/bind/genjava.go b/bind/genjava.go
index 2d9c032..d2af44a 100644
--- a/bind/genjava.go
+++ b/bind/genjava.go
@@ -44,7 +44,7 @@ func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
 	g.Printf("public final go.Seq.Ref ref() { return ref; }\n\n")
 
 	for _, f := range fields {
-		if t := f.Type(); !isSupported(t) {
+		if t := f.Type(); !g.isSupported(t) {
 			g.Printf("// skipped field %s.%s with unsupported type: %T\n\n", f.Name(), t)
 			continue
 		}
@@ -54,7 +54,7 @@ func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
 
 	var isStringer bool
 	for _, m := range methods {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -69,7 +69,7 @@ func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
 	g.Printf("if (o == null || !(o instanceof %s)) {\n    return false;\n}\n", n)
 	g.Printf("%s that = (%s)o;\n", n, n)
 	for _, f := range fields {
-		if t := f.Type(); !isSupported(t) {
+		if t := f.Type(); !g.isSupported(t) {
 			g.Printf("// skipped field %s.%s with unsupported type: %T\n\n", f.Name(), t)
 			continue
 		}
@@ -94,7 +94,7 @@ func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
 	g.Printf("    return java.util.Arrays.hashCode(new Object[] {")
 	idx := 0
 	for _, f := range fields {
-		if t := f.Type(); !isSupported(t) {
+		if t := f.Type(); !g.isSupported(t) {
 			continue
 		}
 		if idx > 0 {
@@ -115,7 +115,7 @@ func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
 		g.Printf(`b.append("%s").append("{");`, obj.Name())
 		g.Printf("\n")
 		for _, f := range fields {
-			if t := f.Type(); !isSupported(t) {
+			if t := f.Type(); !g.isSupported(t) {
 				continue
 			}
 			n := f.Name()
@@ -150,7 +150,7 @@ func (g *javaGen) genInterface(iface interfaceInfo) {
 
 	methodSigErr := false
 	for _, m := range iface.summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", iface.obj.Name(), m.Name())
 			continue
 		}
@@ -168,7 +168,7 @@ func (g *javaGen) genInterface(iface interfaceInfo) {
 	g.Indent()
 
 	for _, m := range iface.summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", iface.obj.Name(), m.Name())
 			continue
 		}
@@ -425,7 +425,7 @@ func (g *javaGen) genFuncSignature(o *types.Func, static, header bool) {
 }
 
 func (g *javaGen) genVar(o *types.Var) {
-	if t := o.Type(); !isSupported(t) {
+	if t := o.Type(); !g.isSupported(t) {
 		g.Printf("// skipped variable %s with unsupported type: %T\n\n", o.Name(), t)
 		return
 	}
@@ -615,7 +615,7 @@ func (g *javaGen) genConst(o *types.Const) {
 }
 
 func (g *javaGen) genJNIField(o *types.TypeName, f *types.Var) {
-	if t := f.Type(); !isSupported(t) {
+	if t := f.Type(); !g.isSupported(t) {
 		g.Printf("// skipped field %s with unsupported type: %T\n\n", o.Name(), t)
 		return
 	}
@@ -644,7 +644,7 @@ func (g *javaGen) genJNIField(o *types.TypeName, f *types.Var) {
 }
 
 func (g *javaGen) genJNIVar(o *types.Var) {
-	if t := o.Type(); !isSupported(t) {
+	if t := o.Type(); !g.isSupported(t) {
 		g.Printf("// skipped variable %s with unsupported type: %T\n\n", o.Name(), t)
 		return
 	}
@@ -671,7 +671,7 @@ func (g *javaGen) genJNIVar(o *types.Var) {
 }
 
 func (g *javaGen) genJNIFunc(o *types.Func, sName string, proxy bool) {
-	if !isSigSupported(o.Type()) {
+	if !g.isSigSupported(o.Type()) {
 		n := o.Name()
 		if sName != "" {
 			n = sName + "." + n
@@ -760,7 +760,7 @@ func (g *javaGen) genRelease(varName string, t types.Type, mode varMode) {
 }
 
 func (g *javaGen) genMethodInterfaceProxy(oName string, m *types.Func) {
-	if !isSigSupported(m.Type()) {
+	if !g.isSigSupported(m.Type()) {
 		g.Printf("// skipped method %s with unsupported parameter or return types\n\n", oName)
 		return
 	}
@@ -827,7 +827,7 @@ func (g *javaGen) genH() error {
 		g.Printf("extern jmethodID proxy_class_%s_%s_cons;\n", g.pkgPrefix, iface.obj.Name())
 		g.Printf("\n")
 		for _, m := range iface.summary.callable {
-			if !isSigSupported(m.Type()) {
+			if !g.isSigSupported(m.Type()) {
 				g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", iface.obj.Name(), m.Name())
 				continue
 			}
@@ -953,7 +953,7 @@ func (g *javaGen) genC() error {
 		g.Printf("jclass proxy_class_%s_%s;\n", g.pkgPrefix, iface.obj.Name())
 		g.Printf("jmethodID proxy_class_%s_%s_cons;\n", g.pkgPrefix, iface.obj.Name())
 		for _, m := range iface.summary.callable {
-			if !isSigSupported(m.Type()) {
+			if !g.isSigSupported(m.Type()) {
 				g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", iface.obj.Name(), m.Name())
 				continue
 			}
@@ -980,7 +980,7 @@ func (g *javaGen) genC() error {
 		g.Printf("proxy_class_%s_%s_cons = (*env)->GetMethodID(env, clazz, \"<init>\", \"(Lgo/Seq$Ref;)V\");\n", g.pkgPrefix, iface.obj.Name())
 		g.Printf("clazz = (*env)->FindClass(env, %q);\n", g.jniClassSigType(iface.obj))
 		for _, m := range iface.summary.callable {
-			if !isSigSupported(m.Type()) {
+			if !g.isSigSupported(m.Type()) {
 				g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", iface.obj.Name(), m.Name())
 				continue
 			}
@@ -1066,7 +1066,7 @@ func (g *javaGen) genJava() error {
 		g.genVar(v)
 	}
 	for _, f := range g.funcs {
-		if !isSigSupported(f.Type()) {
+		if !g.isSigSupported(f.Type()) {
 			g.Printf("// skipped function %s with unsupported parameter or return types\n\n", f.Name())
 			continue
 		}
diff --git a/bind/genobjc.go b/bind/genobjc.go
index e556f33..cf726c4 100644
--- a/bind/genobjc.go
+++ b/bind/genobjc.go
@@ -66,7 +66,7 @@ func (g *objcGen) genGoH() error {
 			continue
 		}
 		for _, m := range i.summary.callable {
-			if !isSigSupported(m.Type()) {
+			if !g.isSigSupported(m.Type()) {
 				g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", i.obj.Name(), m.Name())
 				continue
 			}
@@ -143,7 +143,7 @@ func (g *objcGen) genH() error {
 	if len(g.vars) > 0 {
 		g.Printf("@interface %s : NSObject\n", g.namePrefix)
 		for _, obj := range g.vars {
-			if t := obj.Type(); !isSupported(t) {
+			if t := obj.Type(); !g.isSupported(t) {
 				g.Printf("// skipped variable %s with unsupported type: %T\n\n", obj.Name(), t)
 				continue
 			}
@@ -235,7 +235,7 @@ func (g *objcGen) genM() error {
 	g.Printf("\n")
 
 	for _, obj := range g.funcs {
-		if !isSigSupported(obj.Type()) {
+		if !g.isSigSupported(obj.Type()) {
 			g.Printf("// skipped function %s with unsupported parameter or return types\n\n", obj.Name())
 			continue
 		}
@@ -245,7 +245,7 @@ func (g *objcGen) genM() error {
 
 	for _, i := range g.interfaces {
 		for _, m := range i.summary.callable {
-			if !isSigSupported(m.Type()) {
+			if !g.isSigSupported(m.Type()) {
 				g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", i.obj.Name(), m.Name())
 				continue
 			}
@@ -267,7 +267,7 @@ func (g *objcGen) genM() error {
 }
 
 func (g *objcGen) genVarM(o *types.Var) {
-	if t := o.Type(); !isSupported(t) {
+	if t := o.Type(); !g.isSupported(t) {
 		g.Printf("// skipped variable %s with unsupported type: %T\n\n", o.Name(), t)
 		return
 	}
@@ -477,7 +477,7 @@ func (s *funcSummary) returnsVal() bool {
 }
 
 func (g *objcGen) genFuncH(obj *types.Func) {
-	if !isSigSupported(obj.Type()) {
+	if !g.isSigSupported(obj.Type()) {
 		g.Printf("// skipped function %s with unsupported parameter or return types\n\n", obj.Name())
 		return
 	}
@@ -712,7 +712,7 @@ func (g *objcGen) genInterfaceInterface(obj *types.TypeName, summary ifaceSummar
 	g.Printf("\n")
 	g.Printf("- (id)initWithRef:(id)ref;\n")
 	for _, m := range summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			return
 		}
@@ -730,7 +730,7 @@ func (g *objcGen) genInterfaceH(obj *types.TypeName, t *types.Interface) {
 	}
 	g.Printf("@protocol %s%s\n", g.namePrefix, obj.Name())
 	for _, m := range makeIfaceSummary(t).callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -757,7 +757,7 @@ func (g *objcGen) genInterfaceM(obj *types.TypeName, t *types.Interface) bool {
 	g.Printf("\n")
 
 	for _, m := range summary.callable {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -883,7 +883,7 @@ func (g *objcGen) genStructH(obj *types.TypeName, t *types.Struct) {
 
 	// accessors to exported fields.
 	for _, f := range exportedFields(t) {
-		if t := f.Type(); !isSupported(t) {
+		if t := f.Type(); !g.isSupported(t) {
 			g.Printf("// skipped field %s.%s with unsupported type: %T\n\n", obj.Name(), f.Name(), t)
 			continue
 		}
@@ -894,7 +894,7 @@ func (g *objcGen) genStructH(obj *types.TypeName, t *types.Struct) {
 
 	// exported methods
 	for _, m := range exportedMethodSet(types.NewPointer(obj.Type())) {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
@@ -920,7 +920,7 @@ func (g *objcGen) genStructM(obj *types.TypeName, t *types.Struct) {
 	g.Printf("}\n\n")
 
 	for _, f := range fields {
-		if !isSupported(f.Type()) {
+		if !g.isSupported(f.Type()) {
 			g.Printf("// skipped unsupported field %s with type %T\n\n", f.Name(), f)
 			continue
 		}
@@ -929,7 +929,7 @@ func (g *objcGen) genStructM(obj *types.TypeName, t *types.Struct) {
 	}
 
 	for _, m := range methods {
-		if !isSigSupported(m.Type()) {
+		if !g.isSigSupported(m.Type()) {
 			g.Printf("// skipped method %s.%s with unsupported parameter or return types\n\n", obj.Name(), m.Name())
 			continue
 		}
diff --git a/bind/testpkg/testpkg.go b/bind/testpkg/testpkg.go
index 97dd20e..b9ab811 100644
--- a/bind/testpkg/testpkg.go
+++ b/bind/testpkg/testpkg.go
@@ -23,6 +23,7 @@ import (
 
 	"golang.org/x/mobile/bind/testpkg/secondpkg"
 	"golang.org/x/mobile/bind/testpkg/simplepkg"
+	"golang.org/x/mobile/bind/testpkg/unboundpkg"
 )
 
 const (
@@ -469,3 +470,9 @@ func CallImportedI(i secondpkg.I) {
 func NewSimpleS() *simplepkg.S {
 	return nil
 }
+
+func UnboundS(_ *unboundpkg.S) {
+}
+
+func UnboundI(_ unboundpkg.I) {
+}
diff --git a/bind/testpkg/unboundpkg/unboundpkg.go b/bind/testpkg/unboundpkg/unboundpkg.go
new file mode 100644
index 0000000..985b2cb
--- /dev/null
+++ b/bind/testpkg/unboundpkg/unboundpkg.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package simplepkg is imported from testpkg and tests
+// that references to other, unbound packages, are ignored.
+package unboundpkg
+
+type (
+	S struct{}
+	I interface{}
+)
diff --git a/bind/types.go b/bind/types.go
index 5697dbd..2f368dd 100644
--- a/bind/types.go
+++ b/bind/types.go
@@ -101,52 +101,6 @@ func isErrorType(t types.Type) bool {
 	return types.Identical(t, types.Universe.Lookup("error").Type())
 }
 
-// isSigSupported returns whether the generators can handle a given
-// function signature
-func isSigSupported(t types.Type) bool {
-	sig := t.(*types.Signature)
-	params := sig.Params()
-	for i := 0; i < params.Len(); i++ {
-		if !isSupported(params.At(i).Type()) {
-			return false
-		}
-	}
-	res := sig.Results()
-	for i := 0; i < res.Len(); i++ {
-		if !isSupported(res.At(i).Type()) {
-			return false
-		}
-	}
-	return true
-}
-
-// isSupported returns whether the generators can handle the type.
-func isSupported(t types.Type) bool {
-	if isErrorType(t) {
-		return true
-	}
-	switch t := t.(type) {
-	case *types.Basic:
-		return true
-	case *types.Slice:
-		switch e := t.Elem().(type) {
-		case *types.Basic:
-			return e.Kind() == types.Uint8
-		}
-	case *types.Pointer:
-		switch t.Elem().(type) {
-		case *types.Named:
-			return true
-		}
-	case *types.Named:
-		switch t.Underlying().(type) {
-		case *types.Interface, *types.Pointer:
-			return true
-		}
-	}
-	return false
-}
-
 func isExported(t types.Type) bool {
 	if isErrorType(t) {
 		return true