diff --git a/Cython/Build/Dependencies.py b/Cython/Build/Dependencies.py
index cdb3f3f73594e5125c3c82d2a1d9f510a0d3d09b..2f994f74df129bb51d1422ac1a3f798a412edcf5 100644
--- a/Cython/Build/Dependencies.py
+++ b/Cython/Build/Dependencies.py
@@ -294,7 +294,7 @@ def normalize_existing0(base_dir, rel_paths):
         if path_exists(path):
             normalized.append(os.path.normpath(path))
         else:
-            normalized.append(path)
+            normalized.append(rel)
     return normalized
 
 def resolve_depends(depends, include_dirs):