diff --git a/.travis.yml b/.travis.yml
index 1264e52..5d04291 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
 language: node_js
 node_js:
 - '8'
-script: npm t
\ No newline at end of file
+script: make ci
\ No newline at end of file
diff --git a/Makefile b/Makefile
index c031279..624507b 100644
--- a/Makefile
+++ b/Makefile
@@ -16,4 +16,7 @@ dogfood: compile
 	rm -rf ./.perturb
 	node ./lib/cli -s lib
 
+ci: compile
+	node ./lib/cli -s lib -k 85
+
 .PHONY: test example
diff --git a/src/cli.ts b/src/cli.ts
index abe0a9e..4394a3d 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -22,7 +22,7 @@ program
   .option("-x, --testGlob <testGlob>", "glob for selecting files in test directory")
   .option("-y, --sourceGlob <sourceGlob>", "glob for selecting files in source directory")
   .option("-c, --testCmd <testCmd>", "test command")
-  .option("-k, --killRate", "minimum kill rate to exit with code 0")
+  .option("-k, --killRateMin <i>", "minimum kill rate to exit with code 0", parseInt)
   .option("-u, --runner <runner>", "name of runner or runner plugin")
   .parse(process.argv);
 
@@ -40,6 +40,7 @@ const args: OptionalPerturbConfig = R.pickBy(R.complement(R.isNil), {
   sourceGlob: program.sourceGlob,
   testCmd: program.testCmd,
   runner: program.runner,
+  killRateMin: program.killRateMin,
 });
 
 // sync errors inside perturb don't seem to properly cause a non-zero exit w/o this
@@ -55,6 +56,16 @@ process.on("unhandledRejection", (err) => {
 
 // start!
 (async function main() {
-  const results = await perturb(args);
+  const { results, config } = await perturb(args);
   console.log("DONE -- COUNT:", results.length);
+
+  const killed = results.filter(r => r.error);
+  const killRate = Number((killed.length / results.length).toFixed(4)) * 100;
+
+  if (killRate < config.killRateMin) {
+    console.error(`❌ Mutant kill rate was ${killRate} which is below minimum acceptable value ${config.killRateMin}`)
+    process.exitCode = 1;
+  } else {
+    console.log(`✅ Mutant kill rate was ${killRate} which is above minimum acceptable value ${config.killRateMin}`)
+  }
 })();
\ No newline at end of file
diff --git a/src/index.ts b/src/index.ts
index b30c50c..0c195fc 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -30,22 +30,22 @@ export default async function perturb(inputCfg: OptionalPerturbConfig) {
     "*********************************************************\n",
   );
 
-  const cfg = makeConfig(inputCfg);
+  const config = makeConfig(inputCfg);
 
-  console.log("init with config\n", cfg);
+  console.log("init with config\n", config);
 
-  const { setup, teardown, paths } = fileSystem(cfg);
+  const { setup, teardown, paths } = fileSystem(config);
 
-  const matcher = getMatcher(cfg);
-  const runner = getRunner(cfg.runner);
-  const reporter = getReporter(cfg.reporter);
+  const matcher = getMatcher(config);
+  const runner = getRunner(config.runner);
+  const reporter = getReporter(config.reporter);
   const handler = makeMutantHandler(runner, reporter);
   const locator = locateMutants(mutators.getMutatorsForNode);
 
-  // const testRun: Promise<void> = process.env.SKIP_TEST ? Promise.resolve() : runTest(cfg);
+  // const testRun: Promise<void> = process.env.SKIP_TEST ? Promise.resolve() : runTest(config);
 
   // first run the tests, otherwise why bother at all?
-  await spawnP(cfg.testCmd);
+  await spawnP(config.testCmd);
 
   try {
     // then, set up the "shadow" file system that we'll work against
@@ -109,7 +109,7 @@ export default async function perturb(inputCfg: OptionalPerturbConfig) {
     const metadata = { duration };
 
     if (reporter.onFinish) {
-      reporter.onFinish(results, cfg, metadata);
+      reporter.onFinish(results, config, metadata);
     }
 
     // TODO -- provide some run metadata here:
@@ -117,7 +117,7 @@ export default async function perturb(inputCfg: OptionalPerturbConfig) {
     // runner: string
     // sourceCount: number
 
-    return results;
+    return { results, config };
   } finally {
     await teardown();
   }
diff --git a/src/make-config.ts b/src/make-config.ts
index d3e093d..db4b301 100644
--- a/src/make-config.ts
+++ b/src/make-config.ts
@@ -21,6 +21,8 @@ const defaultConfig: PerturbConfig = {
   reporter: "diff",
   matcher: DEFAULT_MATCHER,
   runner: DEFAULT_RUNNER,
+
+  killRateMin: 0,
 };
 
 export default function makeConfig(userConfig: OptionalPerturbConfig = {}): PerturbConfig {
diff --git a/src/types.ts b/src/types.ts
index 45fac65..8e7e030 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -91,6 +91,8 @@ export interface PerturbConfig {
 
   sourceGlob: string;
   testGlob: string;
+
+  killRateMin: number;
 }
 
 export type OptionalPerturbConfig = Partial<PerturbConfig>;