diff --git a/c/flake.nix b/c/flake.nix
index 4dda845..581e0ed 100644
--- a/c/flake.nix
+++ b/c/flake.nix
@@ -20,6 +20,7 @@
         gcc
         #gccStdenv
         gnumake
+        mpi
 
         # valgrind