diff --git a/pkg/github/pullrequests.go b/pkg/github/pullrequests.go
index 9c2a09875..f2d008869 100644
--- a/pkg/github/pullrequests.go
+++ b/pkg/github/pullrequests.go
@@ -1307,6 +1307,9 @@ func MergePullRequest(t translations.TranslationHelperFunc) inventory.ServerTool
 			if err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
+			if mergeMethod == "" {
+				mergeMethod = "merge"
+			}
 
 			options := &github.PullRequestOptions{
 				CommitTitle: commitTitle,