diff --git a/tools/subagent_spawn b/tools/subagent_spawn
index 78b9401..2c01650 100755
--- a/tools/subagent_spawn
+++ b/tools/subagent_spawn
@@ -59,7 +59,7 @@ backend=${backend}"
 [ -n "$model"   ] && kv="${kv}
 model=${model}"
 
-printf '%s\n' "$kv" > "$OLLIE/s/new" || die "failed to create session"
+/bin/echo "$kv" > "$OLLIE/s/new" || die "failed to create session"
 
 B="$OLLIE/s/$name"
 wait=0.1
@@ -70,7 +70,7 @@ for _ in 1 2 3 4 5 6 7 8; do
 done
 [ -d "$B" ] || die "timeout waiting for session $name"
 
-printf '%s\n' "$prompt" > "$B/prompt" || die "failed to submit prompt"
+/bin/echo "$prompt" > "$B/prompt" || die "failed to submit prompt"
 
 # Clean up JIT agent config now that the server has loaded it.
 # Only remove configs with the jit- prefix (generated by subagent_generate).