diff --git a/image/spec/v1.2.md b/image/spec/v1.2.md
index 63e97de..08b0025 100644
--- a/image/spec/v1.2.md
+++ b/image/spec/v1.2.md
@@ -1,4 +1,4 @@
-# Docker Image Specification v1.1.0
+# Docker Image Specification v1.2.0

 An *Image* is an ordered collection of root filesystem changes and the
 corresponding execution parameters for use within a container runtime. This
@@ -6,7 +6,7 @@ specification outlines the format of these filesystem changes and corresponding
 parameters and describes how to create and use them for use with a container
 runtime and execution tool.

-This version of the image specification was adopted starting in Docker 1.10.
+This version of the image specification was adopted starting in Docker 1.12.

 ## Terminology

@@ -336,6 +336,65 @@ whitespace. It has been added to this example for clarity.
                 array should be interpreted as the executable to run.
             </dd>
             <dt>
+                Healthcheck <code>struct</code>
+            </dt>
+            <dd>
+                A test to perform to determine whether the container is healthy.
+                Here is an example:
+<pre>{
+  "Test": [
+      "CMD-SHELL",
+      "/usr/bin/check-health localhost"
+  ],
+  "Interval": 30000000000,
+  "Timeout": 10000000000,
+  "Retries": 3
+}</pre>
+                The object has the following fields.
+                <dl>
+                    <dt>
+                        Test <code>array of strings</code>
+                    </dt>
+                    <dd>
+                        The test to perform to check that the container is healthy.
+                        The options are:
+                        <ul>
+                            <li><code>{}</code> : inherit healthcheck from base image</li>
+                            <li><code>{"NONE"}</code> : disable healthcheck</li>
+                            <li><code>{"CMD", args...}</code> : exec arguments directly</li>
+                            <li><code>{"CMD-SHELL", command}</code> : run command with system's default shell</li>
+                        </ul>
+
+                        The test command should exit with a status of 0 if the container is healthy,
+                        or with 1 if it is unhealthy.
+                    </dd>
+                    <dt>
+                        Interval <code>integer</code>
+                    </dt>
+                    <dd>
+                        Nanoseconds to wait between probe attempts.
+                    </dd>
+                    <dt>
+                        Timeout <code>integer</code>
+                    </dt>
+                    <dd>
+                        Nanoseconds to wait before considering the check to have hung.
+                    </dd>
+                    <dt>
+                        Retries <code>integer</code>
+                    <dt>
+                    <dd>
+                        The number of consecutive failures needed to consider a container as unhealthy.
+                    </dd>
+                </dl>
+
+                In each case, the field can be omitted to indicate that the
+                value should be inherited from the base layer.
+
+                These values act as defaults and are merged with any specified
+                when creating a container.
+            </dd>
+            <dt>
                 Volumes <code>struct</code>
             </dt>
             <dd>