diff --git a/benchmark/isprime.wrk b/benchmark/isprime.wrk
index 45d3f78..fdb0082 100644
--- a/benchmark/isprime.wrk
+++ b/benchmark/isprime.wrk
@@ -1,2 +1,26 @@
 wrk.method = "POST"
 wrk.body = "107107"
+done = function(summary, latency, requests)
+  -- open output file
+  f = io.open("result.csv", "a+")
+  
+  -- write below results to file
+  --   minimum latency
+  --   max latency
+  --   mean of latency
+  --   standard deviation of latency
+  --   50percentile latency
+  --   90percentile latency
+  --   99percentile latency
+  --   99.999percentile latency
+  --   duration of the benchmark
+  --   total requests during the benchmark
+  --   total received bytes during the benchmark
+  
+  f:write(string.format("%f,%f,%f,%f,%f,%f,%f,%f,%d,%d,%d\n",
+  latency.min, latency.max, latency.mean, latency.stdev, latency:percentile(50),
+  latency:percentile(90), latency:percentile(99), latency:percentile(99.999),
+  summary["duration"], summary["requests"], summary["bytes"]))
+  
+  f:close()
+end