diff --git a/test/run-wasi-test.py b/test/run-wasi-test.py
index 25dfa95..ef16f7a 100755
--- a/test/run-wasi-test.py
+++ b/test/run-wasi-test.py
@@ -4,8 +4,8 @@
 # Usage:
 #   ./run-wasi-test.py
 #   ./run-wasi-test.py --exec ../custom_build/wasm3 --timeout 120
-#   ./run-wasi-test.py --exec "wasmer run --dir=."
-#
+#   ./run-wasi-test.py --exec "wasmer run --mapdir=/:." --separate-args
+#   ./run-wasi-test.py --exec "wasmer run --mapdir=/:. wasm3.wasm --" --fast
 
 import argparse
 import sys
@@ -24,6 +24,7 @@ from pprint import pprint
 
 parser = argparse.ArgumentParser()
 parser.add_argument("--exec", metavar="<interpreter>", default="../build/wasm3")
+parser.add_argument("--separate-args",  action='store_true')      # use "--" separator for wasmer, wasmtime
 parser.add_argument("--timeout", type=int,             default=120)
 parser.add_argument("--fast",    action='store_true')
 
@@ -82,7 +83,7 @@ commands_full = [
     "name":           "Brotli",
     "stdin":          "./benchmark/brotli/alice29.txt",
     "wasm":           "./benchmark/brotli/brotli.wasm",
-    "args":           ["-c"],
+    "args":           ["-c", "-f"],
     "expect_sha1":    "8eacda4b80fc816cad185330caa7556e19643dff"
   }, {
     "name":           "CoreMark",
@@ -134,7 +135,7 @@ commands_fast = [
     "name":           "Brotli",
     "stdin":          "./benchmark/brotli/alice29_small.txt",
     "wasm":           "./benchmark/brotli/brotli.wasm",
-    "args":           ["-c"],
+    "args":           ["-c", "-f"],
     "expect_sha1":    "0e8af02a7207c0c617d7d38eed92853c4a619987"
   }
 ]
@@ -143,11 +144,6 @@ def fail(msg):
     print(f"{ansi.FAIL}FAIL:{ansi.ENDC} {msg}")
     stats.failed += 1
 
-
-args_sep = None
-if "wasmer" in args.exec or "wasmtime" in args.exec:
-    args_sep = "--"
-
 commands = commands_fast if args.fast else commands_full
 
 for cmd in commands:
@@ -157,8 +153,8 @@ for cmd in commands:
     command = args.exec.split(' ')
     command.append(cmd['wasm'])
     if "args" in cmd:
-        if args_sep:
-            command.append(args_sep)
+        if args.separate_args:
+            command.append("--")
         command.extend(cmd['args'])
 
     command = list(map(str, command))
diff --git a/test/wasi/README.md b/test/wasi/README.md
index fac188c..56ae6c1 100644
--- a/test/wasi/README.md
+++ b/test/wasi/README.md
@@ -1,15 +1,8 @@
 ## Compile
 
 ```sh
-wasicc -O3 test.c -o test.wasm
-wasm-opt -O3 test.wasm -o test-opt.wasm
-wasm-strip test-opt.wasm
-```
-
-```sh
-wasicc -O3 test_native_vs_raw.c -o test_native_vs_raw.wasm -Wl,--allow-undefined-file=wasm_api.syms
-wasm-opt -O3 test_native_vs_raw.wasm -o test_native_vs_raw.wasm
-wasm-strip test_native_vs_raw.wasm
+wasicc -g -O0 -Wl,--stack-first test.c -o test.wasm
+wasm-opt --strip-debug -Os test.wasm -o test-opt.wasm
 ```
 
 ## Run
diff --git a/test/wasi/test-opt.wasm b/test/wasi/test-opt.wasm
index 96a7255..fc6ea7c 100644
Binary files a/test/wasi/test-opt.wasm and b/test/wasi/test-opt.wasm differ
diff --git a/test/wasi/test.wasm b/test/wasi/test.wasm
index 1f30600..af39e62 100755
Binary files a/test/wasi/test.wasm and b/test/wasi/test.wasm differ
diff --git a/test/wasi/test_native_vs_raw.c b/test/wasi/test_native_vs_raw.c
deleted file mode 100644
index 8cd00a5..0000000
--- a/test/wasi/test_native_vs_raw.c
+++ /dev/null
@@ -1,65 +0,0 @@
-#include <stdio.h>
-#include <assert.h>
-#include <time.h>
-
-#include "wasm_api.h"
-
-/*
- * Result: "Raw" calls are ~2x faster than native arg "pushers".
- *
- * WARNING: this benchmark no longer works.
- * Native calls were removed along with wasm3_native_sum.
- * It may be useful in future when we implement libffi calls, etc.
- */
-
-static inline
-double get_time() {
-    struct timespec ts; clock_gettime(CLOCK_REALTIME, &ts);
-    return ts.tv_sec * 1000.0 + ts.tv_nsec / 1000000.0;
-}
-
-int main(int argc, char **argv)
-{
-  const unsigned cycles = (argc > 1) ? atol(argv[1]) : 10000000;
-  double beg, end;
-
-  printf("Validation...\n");
-  fflush(stdout);
-
-  // validate
-  assert(wasm3_raw_sum(10, 20, 30, 40)    == 10 + 20 + 30 + 40);
-  assert(wasm3_native_sum(10, 20, 30, 40) == 10 + 20 + 30 + 40);
-
-  printf("Warm-up...\n");
-  fflush(stdout);
-
-  beg = get_time();
-  for (unsigned i = 0; i < cycles/10; i++) {
-      wasm3_raw_sum(10, 20, 30, 40);
-      wasm3_native_sum(10, 20, 30, 40);
-  }
-
-  printf("Running test...\n");
-  fflush(stdout);
-
-  // actual test
-  beg = get_time();
-  for (unsigned i = 0; i < cycles; i++) {
-      wasm3_raw_sum(1, 2, 3, 4);
-  }
-  end = get_time();
-  const double time_raw = (end - beg);
-
-  beg = get_time();
-  for (unsigned i = 0; i < cycles; i++) {
-      wasm3_native_sum(1, 2, 3, 4);
-  }
-  end = get_time();
-  const double time_native = (end - beg);
-
-  printf("Native: %.3f ms\n", time_native);
-  printf("Raw:    %.3f ms\n", time_raw);
-
-  printf("Native/Raw: %.3f\n", time_native/time_raw);
-  return 0;
-}
diff --git a/test/wasi/test_native_vs_raw.wasm b/test/wasi/test_native_vs_raw.wasm
deleted file mode 100755
index 5c0f325..0000000
Binary files a/test/wasi/test_native_vs_raw.wasm and /dev/null differ