diff --git a/ChangeLog b/ChangeLog
index 958a85e36229f6ab5d4eb1d5053bbe98899b9196..5864b1a5c24333b999fc7a620d3e331c23eb5098 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-05-20  Niels Möller  <nisse@lysator.liu.se>
+
+	* nettle-types.h: Include <stddef.h>, for size_t.
+
 2013-05-17  Niels Möller  <nisse@lysator.liu.se>
 
 	* macros.h (ROTL32, ROTL64): Avoid undefined behaviour for zero
diff --git a/nettle-types.h b/nettle-types.h
index 18aeeeef262a2f79761902578a047638dada0319..1989d188fc6bcad28f91f013691aaad28dc8292a 100644
--- a/nettle-types.h
+++ b/nettle-types.h
@@ -23,9 +23,11 @@
 #ifndef NETTLE_TYPES_H
 #define NETTLE_TYPES_H
 
+/* For size_t */
+#include <stddef.h>
+
 /* Pretend these types always exists. Nettle doesn't use them. */
 #define _STDINT_HAVE_INT_FAST32_T 1
-
 #include "nettle-stdint.h"
 
 #ifdef __cplusplus