diff --git a/XI2proto.h b/XI2proto.h
index 1260200..9418357 100644
--- a/XI2proto.h
+++ b/XI2proto.h
@@ -1021,7 +1021,7 @@ typedef struct
     uint8_t     type;                   /**< Always GenericEvent */
     uint8_t     extension;              /**< XI extension offset */
     uint16_t    sequenceNumber;
-    uint32_t    length;                 /**< Length in 4 byte uints */
+    uint32_t    length;                 /**< Length in 4 byte units */
     uint16_t    evtype;                 /**< ::XI_PropertyEvent */
     uint16_t    deviceid;
     Time        time;