diff --git a/mockgen/model/model.go b/mockgen/model/model.go
index 1df8ef3b..c8af9a34 100644
--- a/mockgen/model/model.go
+++ b/mockgen/model/model.go
@@ -354,6 +354,13 @@ func typeFromType(t reflect.Type) (Type, error) {
 	}
 
 	if imp := t.PkgPath(); imp != "" {
+		// PkgPath might return a path that includes "vendor"
+		// These paths do not compile, so we need to remove everything
+		// up to and including "/vendor/"
+		// see https://github.com/golang/go/issues/12019
+		if i := strings.LastIndex(imp, "/vendor/"); i != -1 {
+			imp = imp[i+len("/vendor/"):]
+		}
 		return &NamedType{
 			Package: imp,
 			Type:    t.Name(),
diff --git a/mockgen/tests/vendor_dep/README.md b/mockgen/tests/vendor_dep/README.md
new file mode 100644
index 00000000..9f9217d2
--- /dev/null
+++ b/mockgen/tests/vendor_dep/README.md
@@ -0,0 +1,2 @@
+Test for [Issue#4](https://github.com/golang/mock/issues/4).
+Also see discussion on [#28](https://github.com/golang/mock/pull/28).
diff --git a/mockgen/tests/vendor_dep/doc.go b/mockgen/tests/vendor_dep/doc.go
new file mode 100644
index 00000000..595f679b
--- /dev/null
+++ b/mockgen/tests/vendor_dep/doc.go
@@ -0,0 +1,3 @@
+package vendor_dep
+
+//go:generate mockgen -package vendor_dep -destination mock.go github.com/golang/mock/mockgen/tests/vendor_dep VendorsDep
diff --git a/mockgen/tests/vendor_dep/mock.go b/mockgen/tests/vendor_dep/mock.go
new file mode 100644
index 00000000..aace06e6
--- /dev/null
+++ b/mockgen/tests/vendor_dep/mock.go
@@ -0,0 +1,46 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: github.com/golang/mock/mockgen/tests/vendor_dep (interfaces: VendorsDep)
+
+// Package vendor_dep is a generated GoMock package.
+package vendor_dep
+
+import (
+	a "a"
+	gomock "github.com/golang/mock/gomock"
+	reflect "reflect"
+)
+
+// MockVendorsDep is a mock of VendorsDep interface
+type MockVendorsDep struct {
+	ctrl     *gomock.Controller
+	recorder *MockVendorsDepMockRecorder
+}
+
+// MockVendorsDepMockRecorder is the mock recorder for MockVendorsDep
+type MockVendorsDepMockRecorder struct {
+	mock *MockVendorsDep
+}
+
+// NewMockVendorsDep creates a new mock instance
+func NewMockVendorsDep(ctrl *gomock.Controller) *MockVendorsDep {
+	mock := &MockVendorsDep{ctrl: ctrl}
+	mock.recorder = &MockVendorsDepMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use
+func (m *MockVendorsDep) EXPECT() *MockVendorsDepMockRecorder {
+	return m.recorder
+}
+
+// Foo mocks base method
+func (m *MockVendorsDep) Foo() a.Ifc {
+	ret := m.ctrl.Call(m, "Foo")
+	ret0, _ := ret[0].(a.Ifc)
+	return ret0
+}
+
+// Foo indicates an expected call of Foo
+func (mr *MockVendorsDepMockRecorder) Foo() *gomock.Call {
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Foo", reflect.TypeOf((*MockVendorsDep)(nil).Foo))
+}
diff --git a/mockgen/tests/vendor_dep/vendor/a/a.go b/mockgen/tests/vendor_dep/vendor/a/a.go
new file mode 100644
index 00000000..156f70b1
--- /dev/null
+++ b/mockgen/tests/vendor_dep/vendor/a/a.go
@@ -0,0 +1,10 @@
+package a
+
+type Ifc interface {
+	A(string) string
+	B(int) int
+	C(chan int) chan int
+	D(interface{})
+	E(map[string]interface{})
+	F([]float64)
+}
diff --git a/mockgen/tests/vendor_dep/vendor_dep.go b/mockgen/tests/vendor_dep/vendor_dep.go
new file mode 100644
index 00000000..412636a2
--- /dev/null
+++ b/mockgen/tests/vendor_dep/vendor_dep.go
@@ -0,0 +1,7 @@
+package vendor_dep
+
+import "a"
+
+type VendorsDep interface {
+	Foo() a.Ifc
+}