diff --git a/flake.nix b/flake.nix
index 2add1f4..85647cd 100644
--- a/flake.nix
+++ b/flake.nix
@@ -12,9 +12,12 @@
     nixpkgs-mermaid.follows = "nixpkgs";
     nixpkgs-micron.follows = "nixpkgs";
 
-    # Project builds (CI + local; follow default unless overridden)
+    # Project builds (local dev; follow default unless overridden)
     nixpkgs-projects.follows = "nixpkgs";
+
+    # CI cross-builds (s390x wheels, mermaid images; follow default unless overridden)
+    nixpkgs-ci.follows = "nixpkgs";
   };
 
-  outputs = { self, nixpkgs, nixpkgs-armer, nixpkgs-bim, nixpkgs-howard, nixpkgs-mermaid, nixpkgs-micron, nixpkgs-projects }: { };
+  outputs = { self, nixpkgs, nixpkgs-armer, nixpkgs-bim, nixpkgs-howard, nixpkgs-mermaid, nixpkgs-micron, nixpkgs-projects, nixpkgs-ci }: { };
 }