diff --git a/pkgs/nomarchy-install/nomarchy-install.sh b/pkgs/nomarchy-install/nomarchy-install.sh
index ecab1ec..96ecb72 100644
--- a/pkgs/nomarchy-install/nomarchy-install.sh
+++ b/pkgs/nomarchy-install/nomarchy-install.sh
@@ -70,10 +70,14 @@ export NIX_CONFIG="flake-registry = $SHARE/registry.json"
 
 # With no network, every substituter query is a DNS timeout + retry storm
 # (and tickles a nix goal.cc assertion crash). Everything an install needs
-# is pinned into the ISO — drop substituters entirely when offline.
+# is pinned into the ISO — drop the binary caches and substitute from the
+# live store's daemon instead. The explicit daemon substituter matters:
+# nixos-install builds with --store /mnt and its own "auto?trusted=1"
+# substituter resolves to the TARGET store (i.e. itself), so without
+# this nothing flows from the ISO and nix bootstraps gcc from source.
 if ! timeout 3 bash -c '</dev/tcp/cache.nixos.org/443' 2>/dev/null; then
-    info "No network — disabling binary caches (the ISO carries everything)."
-    NIX_CONFIG+=$'\nsubstituters =\nbuilders ='
+    info "No network — substituting from the ISO store only."
+    NIX_CONFIG+=$'\nsubstituters =\nextra-substituters = daemon?trusted=1\nbuilders ='
 fi
 
 # ─── Disk selection ─────────────────────────────────────────────────────
@@ -439,7 +443,8 @@ set -e
 export PATH=/run/current-system/sw/bin:\$PATH
 export NIX_CONFIG=$(printf '%q' "$NIX_CONFIG")
 out=\$(nix --extra-experimental-features "nix-command flakes" \
-    build --offline --no-link --print-out-paths \
+    build --no-link --print-out-paths \
+    --option substituters "" \
     "/home/$USERNAME/.nomarchy#homeConfigurations.$USERNAME.activationPackage")
 install -d -o "$USERNAME" -g users /nix/var/nix/profiles/per-user/$USERNAME
 install -d -o "$USERNAME" -g users /nix/var/nix/gcroots/per-user/$USERNAME