diff --git a/stubs_test.go b/stubs_test.go
index 410d76c..fcd8b29 100644
--- a/stubs_test.go
+++ b/stubs_test.go
@@ -23,6 +23,11 @@ func (ni *NullInt) Scan(value interface{}) error {
 	switch v := value.(type) {
 	case nil:
 		ni.Integer, ni.Valid = 0, false
+
+	// FIXME int, int8, int16, int32 types are handled here but that should not
+	// be necessary: only int64 is a driver.Value
+	// Unfortunately, the sqlmock testsuite currently relies on that because
+	// sqlmock doesn't properly limits itself internally to pure driver.Value.
 	case int:
 		ni.Integer, ni.Valid = v, true
 	case int8:
@@ -31,6 +36,7 @@ func (ni *NullInt) Scan(value interface{}) error {
 		ni.Integer, ni.Valid = int(v), true
 	case int32:
 		ni.Integer, ni.Valid = int(v), true
+
 	case int64:
 		const maxUint = ^uint(0)
 		const minUint = 0