diff --git a/.gitignore b/.gitignore
index 9daa8247..62adae57 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 .DS_Store
 node_modules
+.nyc_output
diff --git a/README.md b/README.md
index f4ee9194..32a5b35e 100644
--- a/README.md
+++ b/README.md
@@ -14,13 +14,19 @@ The above example will collect coverage for `foo.js` using v8's profiler.
 
 TODO:
 
-- [ ] write logic for converting v8 coverage output to [Istanbul Coverage.json format](https://github.com/gotwarlost/istanbul/blob/master/coverage.json.md).
+- [x] write logic for converting v8 coverage output to [Istanbul Coverage.json format](https://github.com/gotwarlost/istanbul/blob/master/coverage.json.md).
+  * https://github.com/bcoe/v8-to-istanbul
+
 - [ ] talk to Node.js project about silencing messages:
 
    > `Debugger listening on ws://127.0.0.1:56399/e850110a-c5df-41d8-8ef2-400f6829617f`.
 
-- [ ] figure out why `detailed` mode does not appear to be working.
-- [ ] figure out a better way to determine that all processes in event loop
+- [x] figure out why `detailed` mode does not appear to be working.
+  * this is fixed in v8, as long as you start with `--inspect-brk` you
+    can collect coverage in detailed mode.
+- [x] figure out a better way to determine that all processes in event loop
    have terminated (except the inspector session).
-- [ ] process.exit() can't perform an async operation; how can we track coverage
+- [x] process.exit() can't perform an async operation; how can we track coverage
   for scripts that exit?
+  * we can now listen for the `Runtime.executionContextDestroyed` event.
+- [ ]
diff --git a/bin/c8.js b/bin/c8.js
index c62b7f25..91fd8b06 100755
--- a/bin/c8.js
+++ b/bin/c8.js
@@ -1,10 +1,58 @@
 #!/usr/bin/env node
 
 const argv = require('yargs').parse()
+const CRI = require('chrome-remote-interface')
+const getPort = require('get-port');
 const foreground = require('foreground-child')
-const sw = require('spawn-wrap')
+const waitTillPortOpen = require('wait-till-port-open')
 
-if (argv._.length) {
-  sw([require.resolve('./wrap')])
-  foreground(process.argv.slice(2))
+getPort().then(async port => {
+  foreground(
+    ['node', `--inspect-brk=${port}`].concat(process.argv.slice(2)),
+    (done) => {
+      console.info('actually got here')
+    }
+  )
+  try {
+    await waitTillPortOpen(port)
+    const client = await CRI({port: port})
+
+    const {Debugger, Runtime, Profiler} = client
+    await Runtime.runIfWaitingForDebugger()
+    await Runtime.enable()
+    await Profiler.enable()
+    await Profiler.startPreciseCoverage({callCount: true, detailed: true})
+    await Debugger.enable()
+    await Debugger.paused()
+    await Debugger.resume()
+
+    client.on('event', async (message) => {
+      // console.info(message)
+      if (message.method === 'Runtime.executionContextDestroyed') {
+        await outputCoverage(Profiler)
+        client.close()
+      }
+    })
+
+  } catch (err) {
+    console.error(err)
+    process.exit(1)
+  }
+})
+
+async function outputCoverage (Profiler) {
+  const IGNORED_PATHS = [
+    /\/bin\/wrap.js/,
+    /\/node_modules\//,
+    /node-spawn-wrap/
+  ]
+  let {result} = await Profiler.takePreciseCoverage()
+  result = result.filter(coverage => {
+    for (var ignored, i = 0; (ignored = IGNORED_PATHS[i]) !== undefined; i++) {
+      if (ignored.test(coverage.url)) return false
+    }
+    if (!/^\//.test(coverage.url)) return false
+    else return true
+  })
+  console.log(JSON.stringify(result, null, 2))
 }
diff --git a/bin/wrap.js b/bin/wrap.js
deleted file mode 100755
index ce5b4ea5..00000000
--- a/bin/wrap.js
+++ /dev/null
@@ -1,52 +0,0 @@
-const fs = require('fs')
-const sw = require('spawn-wrap')
-const CRI = require('chrome-remote-interface');
-const getPort = require('get-port');
-const inspector = require('inspector')
-
-// if there are N or less active handles
-// in the event loop, dump coverage and exit.
-const EXIT_HANDLE_COUNT = 4
-
-getPort().then(async port => {
-  // start an inspector session on an unused port.
-  inspector.open(port, true)
-  const client = await CRI({port: port})
-  const {Profiler} = client
-  await Profiler.enable()
-  await Profiler.startPreciseCoverage({callCount: true, detailed: true})
-
-  // run the original "main" now that we've started the inspector.
-  sw.runMain()
-
-  // wait for everything in event loop to terminate
-  // except for inspector session.
-  setInterval(() => {
-    const handleCount = process._getActiveHandles().length
-      + process._getActiveRequests().length
-    if (handleCount <= EXIT_HANDLE_COUNT) {
-      outputCoverageAndExit(client, Profiler)
-    }
-  }, 100)
-}).catch(err => {
-  throw err
-})
-
-async function outputCoverageAndExit (client, Profiler) {
-  const IGNORED_PATHS = [
-    /\/bin\/wrap.js/,
-    /\/node_modules\//,
-    /node-spawn-wrap/
-  ]
-  let {result} = await Profiler.takePreciseCoverage()
-  result = result.filter(coverage => {
-    for (var ignored, i = 0; (ignored = IGNORED_PATHS[i]) !== undefined; i++) {
-      if (ignored.test(coverage.url)) return false
-    }
-    if (!/^\//.test(coverage.url)) return false
-    else return true
-  })
-  console.log(JSON.stringify(result, null, 2))
-  client.close()
-  process.exit(process.exitCode || 0)
-}
diff --git a/index.js b/index.js
deleted file mode 100644
index e69de29b..00000000
diff --git a/package-lock.json b/package-lock.json
index 80783278..00c9f188 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -57,27 +57,17 @@
     "async": {
       "version": "1.5.2",
       "resolved": "https://registry.npmjs.org/async/-/async-1.5.2.tgz",
-      "integrity": "sha1-7GphrlZIDAw8skHJVhjiCJL5Zyo=",
-      "dev": true
+      "integrity": "sha1-7GphrlZIDAw8skHJVhjiCJL5Zyo="
     },
     "async-limiter": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/async-limiter/-/async-limiter-1.0.0.tgz",
       "integrity": "sha512-jp/uFnooOiO+L211eZOoSyzpOITMXx1rBITauYykG3BRYPu8h0UcxsPNB04RR5vo4Tyz3+ay17tR6JVf9qzYWg=="
     },
-    "balanced-match": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
-      "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c="
-    },
-    "brace-expansion": {
-      "version": "1.1.8",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.8.tgz",
-      "integrity": "sha1-wHshHHyVLsH479Uad+8NHTmQopI=",
-      "requires": {
-        "balanced-match": "1.0.0",
-        "concat-map": "0.0.1"
-      }
+    "bluebird": {
+      "version": "2.11.0",
+      "resolved": "https://registry.npmjs.org/bluebird/-/bluebird-2.11.0.tgz",
+      "integrity": "sha1-U0uQM8AiyVecVro7Plpcqvu2UOE="
     },
     "builtin-modules": {
       "version": "1.1.1",
@@ -183,11 +173,6 @@
         "dot-prop": "3.0.0"
       }
     },
-    "concat-map": {
-      "version": "0.0.1",
-      "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
-      "integrity": "sha1-2Klr13/Wjfd5OnMDajug1UBdR3s="
-    },
     "concat-stream": {
       "version": "1.6.0",
       "resolved": "https://registry.npmjs.org/concat-stream/-/concat-stream-1.6.0.tgz",
@@ -513,11 +498,6 @@
         "null-check": "1.0.0"
       }
     },
-    "fs.realpath": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
-      "integrity": "sha1-FQStJSMVjKpA20onh8sBQRmU6k8="
-    },
     "get-caller-file": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-1.0.2.tgz",
@@ -594,19 +574,6 @@
         "ini": "1.3.4"
       }
     },
-    "glob": {
-      "version": "7.1.2",
-      "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.2.tgz",
-      "integrity": "sha512-MJTUg1kjuLeQCJ+ccE4Vpa6kKVXkPYJ2mOCQyUuKLcLQsdrMCpBPUi8qVE6+YuaJkozeA9NusTAw3hLr8Xe5EQ==",
-      "requires": {
-        "fs.realpath": "1.0.0",
-        "inflight": "1.0.6",
-        "inherits": "2.0.3",
-        "minimatch": "3.0.4",
-        "once": "1.4.0",
-        "path-is-absolute": "1.0.1"
-      }
-    },
     "graceful-fs": {
       "version": "4.1.11",
       "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.1.11.tgz",
@@ -649,19 +616,11 @@
         "repeating": "2.0.1"
       }
     },
-    "inflight": {
-      "version": "1.0.6",
-      "resolved": "https://registry.npmjs.org/inflight/-/inflight-1.0.6.tgz",
-      "integrity": "sha1-Sb1jMdfQLQwJvJEKEHW6gWW1bfk=",
-      "requires": {
-        "once": "1.4.0",
-        "wrappy": "1.0.2"
-      }
-    },
     "inherits": {
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
-      "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4="
+      "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=",
+      "dev": true
     },
     "ini": {
       "version": "1.3.4",
@@ -914,26 +873,11 @@
       "resolved": "https://registry.npmjs.org/mimic-fn/-/mimic-fn-1.1.0.tgz",
       "integrity": "sha1-5md4PZLonb00KBi1IwudYqZyrRg="
     },
-    "minimatch": {
-      "version": "3.0.4",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-      "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
-      "requires": {
-        "brace-expansion": "1.1.8"
-      }
-    },
     "minimist": {
       "version": "0.0.8",
       "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
-      "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0="
-    },
-    "mkdirp": {
-      "version": "0.5.1",
-      "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
-      "integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
-      "requires": {
-        "minimist": "0.0.8"
-      }
+      "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
+      "dev": true
     },
     "modify-values": {
       "version": "1.0.0",
@@ -978,14 +922,6 @@
       "integrity": "sha1-IQmtx5ZYh8/AXLvUQsrIv7s2CGM=",
       "dev": true
     },
-    "once": {
-      "version": "1.4.0",
-      "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
-      "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
-      "requires": {
-        "wrappy": "1.0.2"
-      }
-    },
     "optimist": {
       "version": "0.6.1",
       "resolved": "https://registry.npmjs.org/optimist/-/optimist-0.6.1.tgz",
@@ -996,11 +932,6 @@
         "wordwrap": "0.0.3"
       }
     },
-    "os-homedir": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/os-homedir/-/os-homedir-1.0.2.tgz",
-      "integrity": "sha1-/7xJiDNuDoM94MFox+8VISGqf7M="
-    },
     "os-locale": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/os-locale/-/os-locale-2.1.0.tgz",
@@ -1049,11 +980,6 @@
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-3.0.0.tgz",
       "integrity": "sha1-zg6+ql94yxiSXqfYENe1mwEP1RU="
     },
-    "path-is-absolute": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/path-is-absolute/-/path-is-absolute-1.0.1.tgz",
-      "integrity": "sha1-F0uSaHNVNP+8es5r9TpanhtcX18="
-    },
     "path-key": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/path-key/-/path-key-2.0.1.tgz",
@@ -1091,6 +1017,14 @@
         "pinkie": "2.0.4"
       }
     },
+    "portscanner": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/portscanner/-/portscanner-1.2.0.tgz",
+      "integrity": "sha1-sUu9olfRTDEPqcwJaCrwLUCWGAI=",
+      "requires": {
+        "async": "1.5.2"
+      }
+    },
     "process-nextick-args": {
       "version": "1.0.7",
       "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-1.0.7.tgz",
@@ -1210,14 +1144,6 @@
         "align-text": "0.1.4"
       }
     },
-    "rimraf": {
-      "version": "2.6.2",
-      "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.6.2.tgz",
-      "integrity": "sha512-lreewLK/BlghmxtfH36YYVg1i8IAce4TI7oao75I1g245+6BctqTVQiBP3YUJ9C6DQOXJmkYR9X9fCLtCOJc5w==",
-      "requires": {
-        "glob": "7.1.2"
-      }
-    },
     "safe-buffer": {
       "version": "5.1.1",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.1.tgz",
@@ -1261,19 +1187,6 @@
         "amdefine": "1.0.1"
       }
     },
-    "spawn-wrap": {
-      "version": "1.4.0",
-      "resolved": "https://registry.npmjs.org/spawn-wrap/-/spawn-wrap-1.4.0.tgz",
-      "integrity": "sha512-2ASeXMB5TG+beYge/4QKZUrYoOtyFBnyUjcOXrDOQbCVgGRjfX0gvk9gs8sXuLtdkpx9Hv0a5TVeZQ/gVpanag==",
-      "requires": {
-        "foreground-child": "1.5.6",
-        "mkdirp": "0.5.1",
-        "os-homedir": "1.0.2",
-        "rimraf": "2.6.2",
-        "signal-exit": "3.0.2",
-        "which": "1.3.0"
-      }
-    },
     "spdx-correct": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/spdx-correct/-/spdx-correct-1.0.2.tgz",
@@ -1611,6 +1524,15 @@
         "spdx-expression-parse": "1.0.4"
       }
     },
+    "wait-till-port-open": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/wait-till-port-open/-/wait-till-port-open-1.0.0.tgz",
+      "integrity": "sha1-cPYksl3MGEiHFEupvt2JyUDGfik=",
+      "requires": {
+        "bluebird": "2.11.0",
+        "portscanner": "1.2.0"
+      }
+    },
     "which": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/which/-/which-1.3.0.tgz",
@@ -1658,11 +1580,6 @@
         }
       }
     },
-    "wrappy": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
-      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8="
-    },
     "ws": {
       "version": "3.2.0",
       "resolved": "https://registry.npmjs.org/ws/-/ws-3.2.0.tgz",
diff --git a/package.json b/package.json
index 8d29122c..06d060e4 100644
--- a/package.json
+++ b/package.json
@@ -25,7 +25,7 @@
     "chrome-remote-interface": "^0.25.2",
     "foreground-child": "^1.5.6",
     "get-port": "^3.2.0",
-    "spawn-wrap": "=1.3.8",
+    "wait-till-port-open": "^1.0.0",
     "yargs": "^10.0.3"
   },
   "devDependencies": {
diff --git a/test/fixtures/c.mjs b/test/fixtures/c.mjs
new file mode 100644
index 00000000..6a325c22
--- /dev/null
+++ b/test/fixtures/c.mjs
@@ -0,0 +1,11 @@
+const foo = true || (9 + 10)
+
+if (true) {
+  const a = 9 + 22
+} else if (foo) {
+  const b = 9 + 10
+} else {
+  console.info('hey')
+}
+
+throw 'cool'