diff --git a/ChangeLog b/ChangeLog
index 64781e5de71647b11344139ef725c1ea26958f6f..28a85b59b13d45444afea6151f1042c4c47e5a0d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2014-05-03  Niels Möller  <nisse@lysator.liu.se>
+
+	* ccm.h (CCM_DIGEST_SIZE): New constant.
+
 2014-04-30  Niels Möller  <nisse@lysator.liu.se>
 
 	* ccm.c (CCM_IV_MAX_SIZE, CCM_IV_MIN_SIZE): Deleted, replaced by
diff --git a/ccm.h b/ccm.h
index 271638b66cac4cf106c925a20055c894ec877bb0..0a742a5c5108561d3603cdef5c54716286f143e1 100644
--- a/ccm.h
+++ b/ccm.h
@@ -89,6 +89,7 @@ extern "C" {
 
 /* For CCM, the block size of the block cipher shall be 128 bits. */
 #define CCM_BLOCK_SIZE  16
+#define CCM_DIGEST_SIZE 16
 #define CCM_MIN_NONCE_SIZE 7
 #define CCM_MAX_NONCE_SIZE 14