diff --git a/test/wasi/README.md b/test/wasi/README.md
index a71e309..8f37d45 100644
--- a/test/wasi/README.md
+++ b/test/wasi/README.md
@@ -1,15 +1,22 @@
 ## Compile
 
 ```sh
-wasicc -Oz wasi_printf.c -o wasi_printf.wasm
-
-# Disassemble:
-wasm2wat wasi_printf.wasm -o wasi_printf.wat
+wasicc -O3 wasi_printf.c -o wasi_printf.wasm
 ```
 
 ## Run
 
 ```sh
 ../../build/wasm3 wasi_printf.wasm _start
+
+$ENGINES_PATH/wasm-micro-runtime/core/iwasm/products/linux/build/iwasm wasi_printf.wasm
+
+$ENGINES_PATH/wac/wax wasi_printf.wasm
+
+$ENGINES_PATH/WAVM/Release/bin/wavm run wasi_printf.wasm
+
+wasmer run wasi_printf.wasm
+
+wasmer-js run wasi_printf.wasm
 ```
 
diff --git a/test/wasi/wasi_printf.c b/test/wasi/wasi_printf.c
index e0a00a6..f7ec4bf 100644
--- a/test/wasi/wasi_printf.c
+++ b/test/wasi/wasi_printf.c
@@ -1,8 +1,48 @@
-#include <stdlib.h>
 #include <stdio.h>
+#include <stdint.h>
+#include <time.h>
 
-int main(int args, char* argv[]) {
-    //puts("Hello world!");
-    printf("Hell%x w%d%s!\n", 0, 0, "rld");
-    return 0;
+#define WASM_EXPORT __attribute__((used)) __attribute__((visibility ("default")))
+
+struct timespec timespec_diff(struct timespec start, struct timespec end)
+{
+  struct timespec temp;
+  if ((end.tv_nsec-start.tv_nsec)<0) {
+    temp.tv_sec = end.tv_sec-start.tv_sec-1;
+    temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
+  } else {
+    temp.tv_sec = end.tv_sec-start.tv_sec;
+    temp.tv_nsec = end.tv_nsec-start.tv_nsec;
+  }
+  return temp;
+}
+
+WASM_EXPORT
+uint32_t fib(uint32_t n)
+{
+  if(n < 2) {
+    return n;
+  }
+  return fib(n-1) + fib(n-2);
+}
+
+int main()
+{
+  struct timespec start, finish;
+
+  // Chew up some CPU time
+  volatile int n=38, result;
+
+  printf("Calculating fib(%d)...\n", n);
+
+  clock_gettime(CLOCK_REALTIME, &start);
+  result = fib(n);
+  clock_gettime(CLOCK_REALTIME, &finish);
+
+  struct timespec delta = timespec_diff(start, finish);
+
+  printf("Finished in: %lu ms\n", (delta.tv_sec*1000) + (delta.tv_nsec/1000000));
+  //printf("ms: %lf\n", delta_s*1000.0 + delta_ns/1000000.0);
+
+  return 0;
 }
diff --git a/test/wasi/wasi_printf.wasm b/test/wasi/wasi_printf.wasm
index 3372771..df44dfe 100755
Binary files a/test/wasi/wasi_printf.wasm and b/test/wasi/wasi_printf.wasm differ