diff --git a/app/decorators/backtrace_line_decorator.rb b/app/decorators/backtrace_line_decorator.rb
index e13edf1..85a0239 100644
--- a/app/decorators/backtrace_line_decorator.rb
+++ b/app/decorators/backtrace_line_decorator.rb
@@ -44,7 +44,9 @@ class BacktraceLineDecorator < Draper::Decorator
   end
 
   def decorated_path
-    file_relative.sub(Backtrace::GEMS_PATH, "<strong>\\1</strong>")
+    path
+      .sub(Backtrace::IN_APP_PATH, '')
+      .sub(Backtrace::GEMS_PATH, "<strong>\\1</strong>")
   end
 
   private
diff --git a/spec/decorators/backtrace_line_decorator_spec.rb b/spec/decorators/backtrace_line_decorator_spec.rb
new file mode 100644
index 0000000..32dde29
--- /dev/null
+++ b/spec/decorators/backtrace_line_decorator_spec.rb
@@ -0,0 +1,30 @@
+describe BacktraceLineDecorator, type: :decorator do
+  let(:backtrace_line) do
+    described_class.new(
+      number: 884,
+      file: '/path/to/file/ea315ea4.rb',
+      method: :instance_eval)
+  end
+  let(:backtrace_line_in_app) do
+    described_class.new(
+      number: 884,
+      file: '[PROJECT_ROOT]/path/to/file/ea315ea4.rb',
+      method: :instance_eval)
+  end
+  let(:app) { Fabricate(:app, github_repo: 'foo/bar') }
+
+  describe '#to_s' do
+    it 'returns a nice string representation of the first line' do
+      expect(backtrace_line.to_s).to eq('/path/to/file/ea315ea4.rb:884')
+    end
+  end
+
+  describe '#link_to_source_file' do
+    it 'adds a link to the source file' do
+      link = backtrace_line_in_app.link_to_source_file(app) { 'mytext' }
+      expect(link).to eq(
+        '<a target="_blank" href="https://github.com/foo/bar/blob/master/pat' \
+        'h/to/file/ea315ea4.rb#L884">mytext</a>')
+    end
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 3fe6063..1bac201 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -50,6 +50,11 @@ RSpec.configure do |config|
     init_haml_helpers
   end
 
+  config.before(:each, type: :decorator) do |_|
+    Draper::ViewContext.current.class_eval { include Haml::Helpers }
+    Draper::ViewContext.current.instance_eval { init_haml_helpers }
+  end
+
   config.infer_spec_type_from_file_location!
 end
 
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