diff --git a/src/main/scala/app/RepositoryViewerController.scala b/src/main/scala/app/RepositoryViewerController.scala
index 2d1b6a3..4ba43cb 100644
--- a/src/main/scala/app/RepositoryViewerController.scala
+++ b/src/main/scala/app/RepositoryViewerController.scala
@@ -213,11 +213,17 @@
     if(repository.commitCount == 0){
       repo.html.guide(repository)
     } else {
-      val revision = if(revstr.isEmpty) repository.repository.defaultBranch else revstr
-
       JGitUtil.withGit(getRepositoryDir(repository.owner, repository.name)){ git =>
-        // get latest commit
-        val revCommit = JGitUtil.getRevCommitFromId(git, git.getRepository.resolve(revision))
+        // get specified commit
+        val (revCommit, revision) = try {
+          val revision = if(revstr.isEmpty) repository.repository.defaultBranch else revstr
+          (JGitUtil.getRevCommitFromId(git, git.getRepository.resolve(revision)), revision)
+        } catch {
+          case e: NullPointerException => {
+            val revision = repository.branchList.head
+            (JGitUtil.getRevCommitFromId(git, git.getRepository.resolve(revision)), revision)
+          }
+        }
         // get files
         val files = JGitUtil.getFileList(git, revision, path)
         // process README.md
@@ -225,20 +231,10 @@
           new String(JGitUtil.getContent(Git.open(getRepositoryDir(repository.owner, repository.name)), file.id, true).get, "UTF-8")
         }
 
-        repo.html.files(
-          // current branch
-          revision,
-          // repository
-          repository,
-          // current path
-          if(path == ".") Nil else path.split("/").toList,
-          // latest commit
-          new JGitUtil.CommitInfo(revCommit),
-          // file list
-          files,
-          // readme
-          readme
-        )
+        repo.html.files(revision, repository,
+          if(path == ".") Nil else path.split("/").toList, // current path
+          new JGitUtil.CommitInfo(revCommit), // latest commit
+          files, readme)
       }
     }
   }