diff --git a/main.go b/main.go
index d58d2fd..d525994 100644
--- a/main.go
+++ b/main.go
@@ -9,7 +9,7 @@ import (
 	"io/ioutil"
 	"os"
 
-	"github.com/matryer/moq/package/moq"
+	"github.com/matryer/moq/pkg/moq"
 )
 
 func main() {
diff --git a/package/moq/importer.go b/pkg/moq/importer.go
similarity index 70%
rename from package/moq/importer.go
rename to pkg/moq/importer.go
index 66c6109..1445459 100644
--- a/package/moq/importer.go
+++ b/pkg/moq/importer.go
@@ -18,6 +18,7 @@ import (
 )
 
 type customImporter struct {
+	source        string
 	imported      map[string]*types.Package
 	base          types.Importer
 	skipTestFiles bool
@@ -43,8 +44,13 @@ func (i *customImporter) Import(path string) (*types.Package, error) {
 	return pkg, nil
 }
 
-func gopathDir(pkg string) (string, error) {
-	for _, gopath := range strings.Split(os.Getenv("GOPATH"), ":") {
+func gopathDir(source, pkg string) (string, error) {
+	// check vendor directory
+	vendorPath, found := vendorPath(source, pkg)
+	if found {
+		return vendorPath, nil
+	}
+	for _, gopath := range gopaths() {
 		absPath, err := filepath.Abs(path.Join(gopath, "src", pkg))
 		if err != nil {
 			return "", err
@@ -53,18 +59,52 @@ func gopathDir(pkg string) (string, error) {
 			return absPath, nil
 		}
 	}
-	return "", fmt.Errorf("%s not in $GOPATH", pkg)
+	return "", fmt.Errorf("%s not in $GOPATH or %s", pkg, path.Join(source, "vendor"))
+}
+
+func vendorPath(source, pkg string) (string, bool) {
+	for {
+		if isGopath(source) {
+			return "", false
+		}
+		var err error
+		source, err = filepath.Abs(source)
+		if err != nil {
+			return "", false
+		}
+		vendorPath, err := filepath.Abs(path.Join(source, "vendor", pkg))
+		if err != nil {
+			return "", false
+		}
+		if dir, err := os.Stat(vendorPath); err == nil && dir.IsDir() {
+			return vendorPath, true
+		}
+		source = filepath.Dir(source)
+	}
 }
 
 func removeGopath(p string) string {
-	for _, gopath := range strings.Split(os.Getenv("GOPATH"), ":") {
+	for _, gopath := range gopaths() {
 		p = strings.Replace(p, path.Join(gopath, "src")+"/", "", 1)
 	}
 	return p
 }
 
+func gopaths() []string {
+	return strings.Split(os.Getenv("GOPATH"), string(filepath.ListSeparator))
+}
+
+func isGopath(path string) bool {
+	for _, p := range gopaths() {
+		if p == path {
+			return true
+		}
+	}
+	return false
+}
+
 func (i *customImporter) fsPkg(pkg string) (*types.Package, error) {
-	dir, err := gopathDir(pkg)
+	dir, err := gopathDir(i.source, pkg)
 	if err != nil {
 		return importOrErr(i.base, pkg, err)
 	}
@@ -118,8 +158,9 @@ func importOrErr(base types.Importer, pkg string, err error) (*types.Package, er
 }
 
 // newImporter returns an importer that will try to import code from gopath before using go/importer.Default and skipping test files
-func newImporter() types.Importer {
+func newImporter(source string) types.Importer {
 	return &customImporter{
+		source:        source,
 		imported:      make(map[string]*types.Package),
 		base:          importer.Default(),
 		skipTestFiles: true,
@@ -138,8 +179,8 @@ func newImporter() types.Importer {
 // stripGopath teks the directory to a package and remove the gopath to get the
 // cannonical package name
 func stripGopath(p string) string {
-	for _, gopath := range strings.Split(os.Getenv("GOPATH"), ":") {
-		p = strings.Replace(p, path.Join(gopath, "src")+"/", "", 1)
+	for _, gopath := range gopaths() {
+		p = strings.TrimPrefix(p, path.Join(gopath, "src")+"/")
 	}
 	return p
 }
diff --git a/package/moq/moq.go b/pkg/moq/moq.go
similarity index 99%
rename from package/moq/moq.go
rename to pkg/moq/moq.go
index c2339ce..a006121 100644
--- a/package/moq/moq.go
+++ b/pkg/moq/moq.go
@@ -76,7 +76,7 @@ func (m *Mocker) Mock(w io.Writer, name ...string) error {
 			files[i] = file
 			i++
 		}
-		conf := types.Config{Importer: newImporter()}
+		conf := types.Config{Importer: newImporter(m.src)}
 		tpkg, err := conf.Check(m.src, m.fset, files, nil)
 		if err != nil {
 			return err
diff --git a/package/moq/moq_test.go b/pkg/moq/moq_test.go
similarity index 83%
rename from package/moq/moq_test.go
rename to pkg/moq/moq_test.go
index 1fad8df..d54d70b 100644
--- a/package/moq/moq_test.go
+++ b/pkg/moq/moq_test.go
@@ -7,7 +7,7 @@ import (
 )
 
 func TestMoq(t *testing.T) {
-	m, err := New("testdata/example", "")
+	m, err := New("testpackages/example", "")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -40,7 +40,7 @@ func TestMoq(t *testing.T) {
 }
 
 func TestMoqExplicitPackage(t *testing.T) {
-	m, err := New("testdata/example", "different")
+	m, err := New("testpackages/example", "different")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -70,7 +70,7 @@ func TestMoqExplicitPackage(t *testing.T) {
 // expected.
 // see https://github.com/matryer/moq/issues/5
 func TestVariadicArguments(t *testing.T) {
-	m, err := New("testdata/variadic", "")
+	m, err := New("testpackages/variadic", "")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -95,7 +95,7 @@ func TestVariadicArguments(t *testing.T) {
 }
 
 func TestNothingToReturn(t *testing.T) {
-	m, err := New("testdata/example", "")
+	m, err := New("testpackages/example", "")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -120,7 +120,7 @@ func TestNothingToReturn(t *testing.T) {
 }
 
 func TestChannelNames(t *testing.T) {
-	m, err := New("testdata/channels", "")
+	m, err := New("testpackages/channels", "")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -141,7 +141,7 @@ func TestChannelNames(t *testing.T) {
 }
 
 func TestImports(t *testing.T) {
-	m, err := New("testdata/imports/two", "")
+	m, err := New("testpackages/imports/two", "")
 	if err != nil {
 		t.Fatalf("moq.New: %s", err)
 	}
@@ -153,7 +153,7 @@ func TestImports(t *testing.T) {
 	s := buf.String()
 	var strs = []string{
 		`	"sync"`,
-		`	"github.com/matryer/moq/package/moq/testdata/imports/one"`,
+		`	"github.com/matryer/moq/pkg/moq/testpackages/imports/one"`,
 	}
 	for _, str := range strs {
 		if !strings.Contains(s, str) {
@@ -171,3 +171,25 @@ func TestTemplateFuncs(t *testing.T) {
 		t.Errorf("exported didn't work: %s", fn("var"))
 	}
 }
+
+func TestVendoredPackages(t *testing.T) {
+	m, err := New("testpackages/vendoring/user", "")
+	if err != nil {
+		t.Fatalf("moq.New: %s", err)
+	}
+	var buf bytes.Buffer
+	err = m.Mock(&buf, "Service")
+	if err != nil {
+		t.Errorf("mock error: %s", err)
+	}
+	s := buf.String()
+	// assertions of things that should be mentioned
+	var strs = []string{
+		`"github.com/matryer/somerepo"`,
+	}
+	for _, str := range strs {
+		if !strings.Contains(s, str) {
+			t.Errorf("expected but missing: \"%s\"", str)
+		}
+	}
+}
diff --git a/package/moq/testdata/channels/example.go b/pkg/moq/testpackages/channels/example.go
similarity index 100%
rename from package/moq/testdata/channels/example.go
rename to pkg/moq/testpackages/channels/example.go
diff --git a/package/moq/testdata/example/example.go b/pkg/moq/testpackages/example/example.go
similarity index 100%
rename from package/moq/testdata/example/example.go
rename to pkg/moq/testpackages/example/example.go
diff --git a/package/moq/testdata/imports/one/one.go b/pkg/moq/testpackages/imports/one/one.go
similarity index 100%
rename from package/moq/testdata/imports/one/one.go
rename to pkg/moq/testpackages/imports/one/one.go
diff --git a/package/moq/testdata/imports/two/two.go b/pkg/moq/testpackages/imports/two/two.go
similarity index 71%
rename from package/moq/testdata/imports/two/two.go
rename to pkg/moq/testpackages/imports/two/two.go
index a7635a6..d5929ee 100644
--- a/package/moq/testdata/imports/two/two.go
+++ b/pkg/moq/testpackages/imports/two/two.go
@@ -1,7 +1,7 @@
 package two
 
 import (
-	"github.com/matryer/moq/package/moq/testdata/imports/one"
+	"github.com/matryer/moq/pkg/moq/testpackages/imports/one"
 )
 
 // DoSomething does something.
diff --git a/package/moq/testdata/variadic/greeter.go b/pkg/moq/testpackages/variadic/greeter.go
similarity index 100%
rename from package/moq/testdata/variadic/greeter.go
rename to pkg/moq/testpackages/variadic/greeter.go
diff --git a/pkg/moq/testpackages/vendoring/user/user.go b/pkg/moq/testpackages/vendoring/user/user.go
new file mode 100644
index 0000000..798f104
--- /dev/null
+++ b/pkg/moq/testpackages/vendoring/user/user.go
@@ -0,0 +1,8 @@
+package user
+
+import "github.com/matryer/somerepo"
+
+// Service does something good with computers.
+type Service interface {
+	DoSomething(somerepo.SomeType) error
+}
diff --git a/pkg/moq/testpackages/vendoring/vendor/github.com/matryer/somerepo/code.go b/pkg/moq/testpackages/vendoring/vendor/github.com/matryer/somerepo/code.go
new file mode 100644
index 0000000..706bf42
--- /dev/null
+++ b/pkg/moq/testpackages/vendoring/vendor/github.com/matryer/somerepo/code.go
@@ -0,0 +1,9 @@
+// Package somerepo is a vendored package to test how moq deals with
+// packages in the vendor package.
+package somerepo
+
+// SomeType is just some old type.
+type SomeType struct {
+	// Truth indicates whether true is true or not. Computers.
+	Truth bool
+}