diff --git a/overlay.nix b/overlay.nix
index fde7798..ace3c8f 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -206,7 +206,7 @@ extraPkgs // {
     postInstall = ''
       ${(old.postInstall or "")}
       non_necessary_binaries=("tc" "rdma" "dcb" "tipc" "vdpa")
-      for needless_binary in "$non_necessary_binaries[@]"; do
+      for needless_binary in "''${non_necessary_binaries[@]}"; do
         echo "Removing unnecessary binary $out/$needless_binary"
         rm "$out/$needless_binary"
       done