diff --git a/CHANGES b/CHANGES
index efeadd2..8b71319 100644
--- a/CHANGES
+++ b/CHANGES
@@ -32,6 +32,7 @@ SVN HEAD
   library: New libi2c library
            Properly propagate real error codes on read errors
            Use I2C_SMBUS_BLOCK_MAX instead of hard-coding 32
+  lib/smbus.c: Add missing include which was causing a build error
 
 3.1.0 (2011-12-04)
   decode-dimms: Decode module configuration type of DDR SDRAM
diff --git a/lib/smbus.c b/lib/smbus.c
index 6108fe6..d23ecff 100644
--- a/lib/smbus.c
+++ b/lib/smbus.c
@@ -22,6 +22,7 @@
 */
 
 #include <errno.h>
+#include <stddef.h>
 #include <i2c/smbus.h>
 #include <sys/ioctl.h>
 #include <linux/types.h>