diff --git a/guix-data-service/web/repository/controller.scm b/guix-data-service/web/repository/controller.scm
index 530d52d..6fbe4ce 100644
--- a/guix-data-service/web/repository/controller.scm
+++ b/guix-data-service/web/repository/controller.scm
@@ -212,6 +212,17 @@
            (render-unknown-revision mime-types
                                     conn
                                     commit-hash))))
+    (('GET "repository" repository-id "branch" branch-name "latest-processed-revision" "package-substitute-availability")
+     (let ((commit-hash
+            (latest-processed-commit-for-branch conn repository-id branch-name)))
+       (if commit-hash
+           (render-revision-package-substitute-availability mime-types
+                                                            conn
+                                                            commit-hash
+                                                            #:path-base path)
+           (render-unknown-revision mime-types
+                                    conn
+                                    commit-hash))))
     (('GET "repository" repository-id "branch" branch-name "latest-processed-revision"
            "lint-warnings")
      (let ((commit-hash
diff --git a/guix-data-service/web/revision/controller.scm b/guix-data-service/web/revision/controller.scm
index 62ddca1..9093d70 100644
--- a/guix-data-service/web/revision/controller.scm
+++ b/guix-data-service/web/revision/controller.scm
@@ -54,6 +54,7 @@
             render-revision-package-version
             render-revision-packages
             render-revision-package-reproduciblity
+            render-revision-package-substitute-availability
             render-revision-package-derivations
             render-unknown-revision
             render-view-revision))