diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index c4cf1ead..f85d479b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -12,6 +12,8 @@ jobs:
         include:
         - ruby-version: 'truffleruby'
           failure-allowed: true
+        - ruby-version: '3.3.0-preview3'
+          failure-allowed: true
     steps:
     - uses: actions/checkout@v4
     - name: Set up Ruby
diff --git a/app/lib/paper_file.rb b/app/lib/paper_file.rb
index b711ee55..e45a4119 100644
--- a/app/lib/paper_file.rb
+++ b/app/lib/paper_file.rb
@@ -64,7 +64,7 @@ def self.find(search_path)
 
     if Dir.exist? search_path
       Find.find(search_path).each do |path|
-        if path =~ /paper\.tex$|paper\.md$/
+        if path =~ /\/paper\.tex$|\/paper\.md$/
           paper_path = path
           break
         end
diff --git a/spec/paper_file_spec.rb b/spec/paper_file_spec.rb
index 5aaf23eb..4727b968 100644
--- a/spec/paper_file_spec.rb
+++ b/spec/paper_file_spec.rb
@@ -144,7 +144,7 @@
 
     it "should return a nil PaperFile if no paper file found" do
       expect(Dir).to receive(:exist?).with("/repo/path/").and_return(true)
-      allow(Find).to receive(:find).with("/repo/path/").and_return(["lib/papers.pdf", "./docs", "app"])
+      allow(Find).to receive(:find).with("/repo/path/").and_return(["lib/papers.pdf", "lib/other_paper.md", "./docs", "app"])
 
       paper_file = PaperFile.find("/repo/path/")