diff --git a/README.md b/README.md
index d2154d61..e7f61ebb 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ Here is the list of the available plugins:
 * **check_cpu** - checks the CPU (user mode) utilization 
 * **check_cpufreq** - displays the CPU frequency characteristics
 * **check_cswch** - checks the total number of context switches across all CPUs
-* **check_docker** - checks the number of running docker containers :new: (:warning: *under development*)
+* **check_docker** - checks the number of running docker containers :new: (:warning: *alpha*)
 * **check_fc** - monitors the status of the fiber status ports
 * **check_ifmountfs** - checks whether the given filesystems are mounted
 * **check_intr** - monitors the total number of system interrupts
diff --git a/plugins/check_docker.c b/plugins/check_docker.c
index be8fb551..33f60055 100644
--- a/plugins/check_docker.c
+++ b/plugins/check_docker.c
@@ -72,7 +72,7 @@ usage (FILE * out)
   fputs
     ("  -i, --image IMAGE   limit the investigation only to the containers "
      "running IMAGE\n", out);
-  fputs ("  -M, --memory    return the runtime memory metrics\n", out);
+  fputs ("  -M, --memory    return the runtime memory metrics (alpha!)\n", out);
   fputs ("  -b,-k,-m,-g     "
          "show output in bytes, KB (the default), MB, or GB\n", out);
   fputs ("  -w, --warning COUNTER    warning threshold\n", out);