diff --git a/mockgen/internal/tests/build_constraint/mock.go b/mockgen/internal/tests/build_constraint/mock.go
index 7d4dba7..7fdd352 100644
--- a/mockgen/internal/tests/build_constraint/mock.go
+++ b/mockgen/internal/tests/build_constraint/mock.go
@@ -19,6 +19,7 @@ import (
 type MockEmpty struct {
 	ctrl     *gomock.Controller
 	recorder *MockEmptyMockRecorder
+	isgomock struct{}
 }
 
 // MockEmptyMockRecorder is the mock recorder for MockEmpty.
@@ -37,8 +38,3 @@ func NewMockEmpty(ctrl *gomock.Controller) *MockEmpty {
 func (m *MockEmpty) EXPECT() *MockEmptyMockRecorder {
 	return m.recorder
 }
-
-// ISGOMOCK indicates that this struct is a gomock mock.
-func (m *MockEmpty) ISGOMOCK() struct{} {
-	return struct{}{}
-}