diff --git a/README.md b/README.md
index e377587..f3a1a37 100644
--- a/README.md
+++ b/README.md
@@ -65,11 +65,13 @@ If you are using the socket URL to access the API, on each monitored host, you'l
 
 Service is running:
 
-    DOCKER OK | events_listeners=0 file_descriptors=10 go_routines=12 images=11 service=0;0;0
+    DOCKER OK | events_listeners=0 file_descriptors=20 go_routines=33 images=0 service=1;1:1;1:1
 
 Service is not running:
 
-	DOCKER CRITICAL - (outside range 0:0) | service=1;0;0
+    DOCKER CRITICAL - outside range 1:1 | service=0;1:1;1:1
+
+Mind you that the latter is also returned when the user running this plugin lacks sufficient privileges to run `docker info`.
 
 The following stats are returned:
 
@@ -97,6 +99,3 @@ To install this you can run:
 ### User Interface
 
 ![image](screenshot.png)
-
-
-
diff --git a/check_docker b/check_docker
index 3194032..8b64d3e 100755
--- a/check_docker
+++ b/check_docker
@@ -44,7 +44,7 @@ class Docker(nagiosplugin.Resource):
 
             metrics = [
                 nagiosplugin.Metric(
-                    'service', self.docker_running),
+                    'service', int(self.docker_running)),
                 nagiosplugin.Metric('images', self.images, context='default'),
                 nagiosplugin.Metric(
                     'go_routines', self.go_routines, context='default'),
@@ -55,7 +55,7 @@ class Docker(nagiosplugin.Resource):
             ]
 
         else:
-            metrics = [nagiosplugin.Metric('service', self.docker_running)]
+            metrics = [nagiosplugin.Metric('service', int(self.docker_running))]
 
         return metrics
 
@@ -85,9 +85,9 @@ def main():
 
     args = argp.parse_args()
 
-    # create our check object, if service metric !=0, consider that critical.
+    # create our check object, if service metric !=1 (True), consider that critical.
     check = nagiosplugin.Check(Docker(args.url, args.api_version),
-                               nagiosplugin.ScalarContext('service', '0', '0', fmt_metric=''),
+                               nagiosplugin.ScalarContext('service', '1:1', '1:1', fmt_metric=''),
                                DockerSummary())
 
     check.main(args.verbose, args.timeout)