diff --git a/mockgen/parse.go b/mockgen/parse.go
index 794e749d..3060c481 100644
--- a/mockgen/parse.go
+++ b/mockgen/parse.go
@@ -444,13 +444,13 @@ func importsOfFile(file *ast.File) map[string]string {
 			pkg, err := build.Import(importPath, "", 0)
 			if err != nil {
 				// Fallback to import path suffix. Note that this is uncertain.
-				log.Printf("failed to import package by path %s: %s - fallback to import path suffix", importPath, err.Error())
 				_, last := path.Split(importPath)
 				// If the last path component has dots, the first dot-delimited
 				// field is used as the name.
 				pkgName = strings.SplitN(last, ".", 2)[0]
+			} else {
+				pkgName = pkg.Name
 			}
-			pkgName = pkg.Name
 		}
 
 		if _, ok := m[pkgName]; ok {
diff --git a/mockgen/tests/vendor_dep/doc.go b/mockgen/tests/vendor_dep/doc.go
index 595f679b..e751826d 100644
--- a/mockgen/tests/vendor_dep/doc.go
+++ b/mockgen/tests/vendor_dep/doc.go
@@ -1,3 +1,4 @@
 package vendor_dep
 
 //go:generate mockgen -package vendor_dep -destination mock.go github.com/golang/mock/mockgen/tests/vendor_dep VendorsDep
+//go:generate mockgen -destination source_mock_package/mock.go -source=vendor_dep.go
diff --git a/mockgen/tests/vendor_dep/source_mock_package/mock.go b/mockgen/tests/vendor_dep/source_mock_package/mock.go
new file mode 100644
index 00000000..b4732592
--- /dev/null
+++ b/mockgen/tests/vendor_dep/source_mock_package/mock.go
@@ -0,0 +1,46 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: vendor_dep.go
+
+// Package mock_vendor_dep is a generated GoMock package.
+package mock_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))
+}