diff --git a/README.md b/README.md
index adea676..ed59828 100644
--- a/README.md
+++ b/README.md
@@ -60,7 +60,7 @@ All you need to give is just health check function returning cats `ValidationNel
 
   val response = Http().singleRequest(HttpRequest(uri = "http://localhost:8888/health"))
 
-  // status code is 200(OK) if healthy, 500(Internal Server Error) if unhealthy.
+  // status code is 200(OK) if healthy, 503(Service Unavailable) if unhealthy.
   // response body is empty by default for performance.
   // pass '?full=true' query parameter to see full check result as json. it would be similar to below.
   // Please see com.github.everpeace.healthchecks.HealthRoutesTest for various response patterns.
diff --git a/core/src/main/scala/com/github/everpeace/healthchecks/route/HealthCheckRoutes.scala b/core/src/main/scala/com/github/everpeace/healthchecks/route/HealthCheckRoutes.scala
index 341008f..e6b9419 100644
--- a/core/src/main/scala/com/github/everpeace/healthchecks/route/HealthCheckRoutes.scala
+++ b/core/src/main/scala/com/github/everpeace/healthchecks/route/HealthCheckRoutes.scala
@@ -54,7 +54,7 @@ object HealthCheckRoutes extends DecorateAsScala {
 
   private def status(s: Boolean) = if (s) "healthy" else "unhealthy"
 
-  private def statusCode(s: Boolean) = if (s) OK else InternalServerError
+  private def statusCode(s: Boolean) = if (s) OK else ServiceUnavailable
 
   private def toResultJson(check: HealthCheck, result: HealthCheckResult) =
     HealthCheckResultJson(
diff --git a/core/src/test/scala/com/github/everpeace/healthchecks/HealthCheckRoutesTest.scala b/core/src/test/scala/com/github/everpeace/healthchecks/HealthCheckRoutesTest.scala
index f6fd2b5..133de22 100644
--- a/core/src/test/scala/com/github/everpeace/healthchecks/HealthCheckRoutesTest.scala
+++ b/core/src/test/scala/com/github/everpeace/healthchecks/HealthCheckRoutesTest.scala
@@ -113,12 +113,12 @@ class HealthRoutesTest
       val failedFatal = healthCheck("test3")(throw new Exception("exception"))
 
       Get("/health") ~> HealthCheckRoutes.health(ok, failedButNonFatal, failedFatal) ~> check {
-        status shouldEqual InternalServerError
+        status shouldEqual ServiceUnavailable
         responseAs[String] shouldEqual "{}"
       }
 
       Get("/health?full=true") ~> HealthCheckRoutes.health(ok, failedButNonFatal, failedFatal) ~> check {
-        status shouldEqual InternalServerError
+        status shouldEqual ServiceUnavailable
         responseAs[String] shouldEqual
           """
             |{