diff --git a/scripts/bench-spec-stack.sh b/scripts/bench-spec-stack.sh
index 1f00c48..0f7893d 100644
--- a/scripts/bench-spec-stack.sh
+++ b/scripts/bench-spec-stack.sh
@@ -19,6 +19,11 @@ OUT_TOKENS="${3:-256}"
 ENV_FILE=/home/dank/vllmScripts/scripts/frank-default-large.env
 source "$ENV_FILE"
 
+# Derive the PromptForge sidecar paths from the env base values.
+export PROMPTFORGE_SIDECAR="$MODEL_DIR/$FFN_PFS"
+export PROMPTFORGE_GDN_SIDECAR="$MODEL_DIR/$GDN_PFS"
+export PROMPTFORGE_MTP_OUTPUT_K8_PROXY="$MODEL_DIR/$OUTPUT_K8_PFS"
+
 MODEL="$MODEL_DIR/$MODEL_FILE"
 LLAMA_BIN=/home/dank/ciru-qwen38/ROCmFPX/build-promptforge/bin/llama-server
 PORT=7893
@@ -33,7 +38,7 @@ for f in "$MODEL" "$PROMPTFORGE_SIDECAR" "$PROMPTFORGE_GDN_SIDECAR" "$PROMPTFORG
 done
 [[ -x "$LLAMA_BIN" ]] || { echo "missing: $LLAMA_BIN" >&2; exit 1; }
 
-export PROMPTFORGE_SIDECAR PROMPTFORGE_GDN_SIDECAR PROMPTFORGE_MODE
+export PROMPTFORGE_MODE="m2048_fused_tail1476"
 export GGML_CUDA_GRAPH_OPT=0
 export PROMPTFORGE_ENABLE_SMALLM_W8=1
 export PROMPTFORGE_MTP_OUTPUT_K8=1