diff --git a/doc/go1compat.html b/doc/go1compat.html
index 04a6c1124b..94c48d2ce3 100644
--- a/doc/go1compat.html
+++ b/doc/go1compat.html
@@ -104,6 +104,14 @@ outside of tests, and using it may cause a program to fail
 to compile in future releases.
 </li>
 
+<li>
+Use of package <code>unsafe</code>. Packages that import
+<a href="/pkg/unsafe/"><code>unsafe</code></a>
+may depend on internal properties of the Go implementation.
+We reserve the right to make changes to the implementation
+that may break such programs.
+</li>
+
 </ul>
 
 <p>
diff --git a/src/unsafe/unsafe.go b/src/unsafe/unsafe.go
index 83b2e14052..79499b2955 100644
--- a/src/unsafe/unsafe.go
+++ b/src/unsafe/unsafe.go
@@ -4,6 +4,9 @@
 
 /*
 	Package unsafe contains operations that step around the type safety of Go programs.
+
+	Packages that import unsafe may be non-portable and are not protected by the
+	Go 1 compatibility guidelines.
 */
 package unsafe