diff --git a/src/Gitonomy/Git/Parser/ParserBase.php b/src/Gitonomy/Git/Parser/ParserBase.php
index be149bf..45a8002 100644
--- a/src/Gitonomy/Git/Parser/ParserBase.php
+++ b/src/Gitonomy/Git/Parser/ParserBase.php
@@ -25,7 +25,7 @@ abstract protected function doParse();
     public function parse($content)
     {
         $this->cursor = 0;
-        $this->content = $content;
+        $this->content = $content ?? '';
         $this->length = strlen($this->content);
 
         $this->doParse();
diff --git a/src/Gitonomy/Git/ReferenceBag.php b/src/Gitonomy/Git/ReferenceBag.php
index adde82c..71ef9ae 100644
--- a/src/Gitonomy/Git/ReferenceBag.php
+++ b/src/Gitonomy/Git/ReferenceBag.php
@@ -354,7 +354,7 @@ protected function initialize()
             $parser = new Parser\ReferenceParser();
             $output = $this->repository->run('show-ref');
         } catch (RuntimeException $e) {
-            $output = null;
+            return;
         }
         $parser->parse($output);
 
diff --git a/tests/Gitonomy/Git/Tests/ReferenceBagTest.php b/tests/Gitonomy/Git/Tests/ReferenceBagTest.php
index 35756bf..f9b9c82 100644
--- a/tests/Gitonomy/Git/Tests/ReferenceBagTest.php
+++ b/tests/Gitonomy/Git/Tests/ReferenceBagTest.php
@@ -44,4 +44,13 @@ public function testUnknownReference(Repository $repository)
         $this->assertArrayNotHasKey('refs/pull/1/head', $refs);
         $this->assertArrayNotHasKey('refs/notes/gtm-data', $refs);
     }
+
+    /**
+     * @dataProvider provideEmpty
+     */
+    public function testEmptyRepo(Repository $repository)
+    {
+        $refs = $repository->getReferences()->getAll();
+        $this->assertSame([], $refs);
+    }
 }