diff --git a/admin/ChangeLog b/admin/ChangeLog
index ec6448dbeee..44856f4b449 100644
--- a/admin/ChangeLog
+++ b/admin/ChangeLog
@@ -1,3 +1,12 @@
+2012-06-24  Dmitry Antipov  <dmantipov@yandex.ru>
+
+	First Coccinelle semantic patch.
+	* coccinelle: New subdirectory
+	* coccinelle/README: Documentation stub.
+	* coccinelle/vector_contents.cocci: Semantic patch to replace direct
+        access to `contents' member of Lisp_Vector objects with AREF and ASET
+        where appropriate.
+
 2012-06-22  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Support higher-resolution time stamps (Bug#9000).
diff --git a/admin/coccinelle/README b/admin/coccinelle/README
new file mode 100644
index 00000000000..48a88dbc8d8
--- /dev/null
+++ b/admin/coccinelle/README
@@ -0,0 +1,3 @@
+This directory contains semantic patches for Coccinelle, a program matching
+and transformation tool for programs written in C.  For more details, see
+http://coccinelle.lip6.fr.
diff --git a/admin/coccinelle/vector_contents.cocci b/admin/coccinelle/vector_contents.cocci
new file mode 100644
index 00000000000..beebc2d2089
--- /dev/null
+++ b/admin/coccinelle/vector_contents.cocci
@@ -0,0 +1,16 @@
+// Avoid direct access to `contents' member of
+// Lisp_Vector, use AREF and ASET where possible.
+@expression@
+identifier I1, I2;
+expression E1, E2;
+@@
+(
+- XVECTOR (I1)->contents[I2++] = E1
++ ASET (I1, I2, E1), I2++
+|
+- XVECTOR (I1)->contents[E1] = E2
++ ASET (I1, E1, E2)
+|
+-XVECTOR (I1)->contents[E1]
++AREF (I1, E1)
+)