diff --git a/convert.go b/convert.go
index 87f0d3f1..5748e379 100644
--- a/convert.go
+++ b/convert.go
@@ -247,3 +247,40 @@ func convertAssign(dest, src interface{}) error {
 
 	return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
 }
+
+func asKind(vv reflect.Value, tp reflect.Type) (interface{}, error) {
+	switch tp.Kind() {
+	case reflect.Int64:
+		return vv.Int(), nil
+	case reflect.Int:
+		return int(vv.Int()), nil
+	case reflect.Int32:
+		return int32(vv.Int()), nil
+	case reflect.Int16:
+		return int16(vv.Int()), nil
+	case reflect.Int8:
+		return int8(vv.Int()), nil
+	case reflect.Uint64:
+		return vv.Uint(), nil
+	case reflect.Uint:
+		return uint(vv.Uint()), nil
+	case reflect.Uint32:
+		return uint32(vv.Uint()), nil
+	case reflect.Uint16:
+		return uint16(vv.Uint()), nil
+	case reflect.Uint8:
+		return uint8(vv.Uint()), nil
+	case reflect.String:
+		return vv.String(), nil
+	case reflect.Slice:
+		if tp.Elem().Kind() == reflect.Uint8 {
+			v, err := strconv.ParseInt(string(vv.Interface().([]byte)), 10, 64)
+			if err != nil {
+				return nil, err
+			}
+			return v, nil
+		}
+
+	}
+	return nil, fmt.Errorf("unsupported primary key type: %v, %v", tp, vv)
+}
diff --git a/session.go b/session.go
index f3619b76..186daeaa 100644
--- a/session.go
+++ b/session.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"hash/crc32"
 	"reflect"
-	"strconv"
 	"strings"
 	"time"
 
@@ -614,34 +613,10 @@ func (session *Session) row2Bean(rows *core.Rows, fields []string, fieldsCount i
 							panic("unsupported non or composited primary key cascade")
 						}
 						var pk = make(core.PK, len(table.PrimaryKeys))
-
-						switch rawValueType.Kind() {
-						case reflect.Int64:
-							pk[0] = vv.Int()
-						case reflect.Int:
-							pk[0] = int(vv.Int())
-						case reflect.Int32:
-							pk[0] = int32(vv.Int())
-						case reflect.Int16:
-							pk[0] = int16(vv.Int())
-						case reflect.Int8:
-							pk[0] = int8(vv.Int())
-						case reflect.Uint64:
-							pk[0] = vv.Uint()
-						case reflect.Uint:
-							pk[0] = uint(vv.Uint())
-						case reflect.Uint32:
-							pk[0] = uint32(vv.Uint())
-						case reflect.Uint16:
-							pk[0] = uint16(vv.Uint())
-						case reflect.Uint8:
-							pk[0] = uint8(vv.Uint())
-						case reflect.String:
-							pk[0] = vv.String()
-						case reflect.Slice:
-							pk[0], _ = strconv.ParseInt(string(rawValue.Interface().([]byte)), 10, 64)
-						default:
-							panic(fmt.Sprintf("unsupported primary key type: %v, %v", rawValueType, fieldValue))
+						var err error
+						pk[0], err = asKind(vv, rawValueType)
+						if err != nil {
+							return nil, err
 						}
 
 						if !isPKZero(pk) {