diff --git a/spec-0000/index.md b/spec-0000/index.md
index 8017c5a2..ca9373da 100644
--- a/spec-0000/index.md
+++ b/spec-0000/index.md
@@ -19,6 +19,7 @@ endorsed-by:
   - numpy
   - scikit-image
   - scipy
+  - xarray
 ---
 
 ## Description
diff --git a/spec-0004/index.md b/spec-0004/index.md
index 3b5f20c8..037331cf 100644
--- a/spec-0004/index.md
+++ b/spec-0004/index.md
@@ -17,6 +17,7 @@ endorsed-by:
   - scikit-image
   - scipy
   - IPython
+  - xarray
 ---
 
 ## Description