diff --git a/ChangeLog b/ChangeLog
index ca9322bddb14cfaa7a6385aff034a5f7ae74ab40..f9165a01c8dbf2fa20f360082de7874a1215b157 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-04-18  Niels Möller  <nisse@lysator.liu.se>
+
+	* umac.h (UMAC32_DIGEST_SIZE, UMAC64_DIGEST_SIZE)
+	(UMAC96_DIGEST_SIZE, UMAC128_DIGEST_SIZE): New constants.
+
 2013-04-17  Niels Möller  <nisse@lysator.liu.se>
 
 	* examples/nettle-benchmark.c (main): Benchmark salsa20r12.
diff --git a/umac.h b/umac.h
index 339130deba55d2d334eae5e411222eb1ff47709e..fcd3ad18d45eed8e635f0b0aaad663eac9a596d6 100644
--- a/umac.h
+++ b/umac.h
@@ -61,8 +61,12 @@ extern "C" {
 #include "nettle-types.h"
 #include "aes.h"
 
-#define UMAC_BLOCK_SIZE 1024
 #define UMAC_KEY_SIZE 16
+#define UMAC32_DIGEST_SIZE 4
+#define UMAC64_DIGEST_SIZE 8
+#define UMAC96_DIGEST_SIZE 12
+#define UMAC128_DIGEST_SIZE 16
+#define UMAC_BLOCK_SIZE 1024
 
 /* Subkeys and state for UMAC with tag size 32*n bits. */
 #define _UMAC_STATE(n)					\