diff --git a/modules/indexer/issues/dboptions.go b/modules/indexer/issues/dboptions.go
index 4a98b4588a..15363847ce 100644
--- a/modules/indexer/issues/dboptions.go
+++ b/modules/indexer/issues/dboptions.go
@@ -38,6 +38,12 @@ func ToSearchOptions(keyword string, opts *issues_model.IssuesOptions) *SearchOp
 		searchOpt.MilestoneIDs = opts.MilestoneIDs
 	}
 
+	if opts.ProjectID > 0 {
+		searchOpt.ProjectID = optional.Some(opts.ProjectID)
+	} else if opts.ProjectID == -1 { // FIXME: this is inconsistent from other places
+		searchOpt.ProjectID = optional.Some[int64](0) // Those issues with no project(projectid==0)
+	}
+
 	// See the comment of issues_model.SearchOptions for the reason why we need to convert
 	convertID := func(id int64) optional.Option[int64] {
 		if id > 0 {
@@ -49,7 +55,6 @@ func ToSearchOptions(keyword string, opts *issues_model.IssuesOptions) *SearchOp
 		return nil
 	}
 
-	searchOpt.ProjectID = convertID(opts.ProjectID)
 	searchOpt.ProjectBoardID = convertID(opts.ProjectBoardID)
 	searchOpt.PosterID = convertID(opts.PosterID)
 	searchOpt.AssigneeID = convertID(opts.AssigneeID)