diff --git a/stubs_test.go b/stubs_test.go
index d3c6003..fcd8b29 100644
--- a/stubs_test.go
+++ b/stubs_test.go
@@ -2,6 +2,7 @@ package sqlmock
 
 import (
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"strconv"
 	"time"
@@ -18,28 +19,50 @@ type NullInt struct {
 }
 
 // Satisfy sql.Scanner interface
-func (ni *NullInt) Scan(value interface{}) (err error) {
-	if value == nil {
-		ni.Integer, ni.Valid = 0, false
-		return
-	}
-
+func (ni *NullInt) Scan(value interface{}) error {
 	switch v := value.(type) {
-	case int, int8, int16, int32, int64:
-		ni.Integer, ni.Valid = v.(int), true
-		return
-	case []byte:
-		ni.Integer, err = strconv.Atoi(string(v))
-		ni.Valid = (err == nil)
-		return
-	case string:
-		ni.Integer, err = strconv.Atoi(v)
-		ni.Valid = (err == nil)
-		return
-	}
+	case nil:
+		ni.Integer, ni.Valid = 0, false
 
-	ni.Valid = false
-	return fmt.Errorf("Can't convert %T to integer", value)
+	// 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:
+		ni.Integer, ni.Valid = int(v), true
+	case int16:
+		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
+		const maxInt = int(maxUint >> 1)
+		const minInt = -maxInt - 1
+
+		if v > int64(maxInt) || v < int64(minInt) {
+			return errors.New("value out of int range")
+		}
+		ni.Integer, ni.Valid = int(v), true
+	case []byte:
+		n, err := strconv.Atoi(string(v))
+		if err != nil {
+			return err
+		}
+		ni.Integer, ni.Valid = n, true
+	case string:
+		n, err := strconv.Atoi(v)
+		if err != nil {
+			return err
+		}
+		ni.Integer, ni.Valid = n, true
+	default:
+		return fmt.Errorf("can't convert %T to integer", value)
+	}
+	return nil
 }
 
 // Satisfy sql.Valuer interface.
@@ -47,24 +70,20 @@ func (ni NullInt) Value() (driver.Value, error) {
 	if !ni.Valid {
 		return nil, nil
 	}
-	return ni.Integer, nil
+	return int64(ni.Integer), nil
 }
 
 // Satisfy sql.Scanner interface
-func (nt *NullTime) Scan(value interface{}) (err error) {
-	if value == nil {
-		nt.Time, nt.Valid = time.Time{}, false
-		return
-	}
-
+func (nt *NullTime) Scan(value interface{}) error {
 	switch v := value.(type) {
+	case nil:
+		nt.Time, nt.Valid = time.Time{}, false
 	case time.Time:
 		nt.Time, nt.Valid = v, true
-		return
+	default:
+		return fmt.Errorf("can't convert %T to time.Time", value)
 	}
-
-	nt.Valid = false
-	return fmt.Errorf("Can't convert %T to time.Time", value)
+	return nil
 }
 
 // Satisfy sql.Valuer interface.