diff --git a/common/test_utils.h b/common/test_utils.h
index 2c8a6de..60ec90e 100644
--- a/common/test_utils.h
+++ b/common/test_utils.h
@@ -90,6 +90,9 @@
   return chdir(path.c_str());
 }
 
+// Reads a symlink from disk. Returns empty string on failure.
+std::string Readlink(const std::string& path);
+
 // Checks if xattr is supported in the directory specified by
 // |dir_path| which must be writable. Returns true if the feature is
 // supported, false if not or if an error occurred.