diff --git a/src/rdb.h b/src/rdb.h
index bf115045..ecb066fb 100644
--- a/src/rdb.h
+++ b/src/rdb.h
@@ -69,8 +69,9 @@
 #define RDB_ENC_INT32 2       /* 32 bit signed integer */
 #define RDB_ENC_LZF 3         /* string compressed with FASTLZ */
 
-/* Dup object types to RDB object types. Only reason is readability (are we
- * dealing with RDB types or with in-memory object types?). */
+/* Map object types to RDB object types. Macros starting with OBJ_ are for
+ * memory storage and may change. Instead RDB types must be fixed because
+ * we store them on disk. */
 #define RDB_TYPE_STRING 0
 #define RDB_TYPE_LIST   1
 #define RDB_TYPE_SET    2
diff --git a/src/server.h b/src/server.h
index 38a76d00..1185d119 100644
--- a/src/server.h
+++ b/src/server.h
@@ -447,12 +447,11 @@ typedef long long mstime_t; /* millisecond time type. */
 /* A redis object, that is a type able to hold a string / list / set */
 
 /* The actual Redis Object */
-#define OBJ_STRING 0
-#define OBJ_LIST 1
-#define OBJ_SET 2
-#define OBJ_ZSET 3
-#define OBJ_HASH 4
-#define OBJ_STREAM 5
+#define OBJ_STRING 0    /* String object. */
+#define OBJ_LIST 1      /* List object. */
+#define OBJ_SET 2       /* Set object. */
+#define OBJ_ZSET 3      /* Sorted set object. */
+#define OBJ_HASH 4      /* Hash object. */
 
 /* The "module" object type is a special one that signals that the object
  * is one directly managed by a Redis module. In this case the value points
@@ -465,7 +464,8 @@ typedef long long mstime_t; /* millisecond time type. */
  * by a 64 bit module type ID, which has a 54 bits module-specific signature
  * in order to dispatch the loading to the right module, plus a 10 bits
  * encoding version. */
-#define OBJ_MODULE 5
+#define OBJ_MODULE 5    /* Module object. */
+#define OBJ_STREAM 6    /* Stream object. */
 
 /* Extract encver / signature from a module type ID. */
 #define REDISMODULE_TYPE_ENCVER_BITS 10
diff --git a/src/t_stream.c b/src/t_stream.c
index c64f5059..dcf9fcce 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -149,7 +149,13 @@ void streamAppendItem(stream *s, robj **argv, int numfields, streamID *added_id)
         memcpy(rax_key,ri.key,sizeof(rax_key));
     }
 
-    /* Populate the listpack with the new entry. */
+    /* Populate the listpack with the new entry. We use the following
+     * encoding:
+     *
+     * +--------+----------+-------+-------+-/-+-------+-------+
+     * |entry-id|num-fields|field-1|value-1|...|field-N|value-N|
+     * +--------+----------+-------+-------+-/-+-------+-------+
+     */
     lp = lpAppend(lp,(unsigned char*)entry_id,sizeof(entry_id));
     lp = lpAppendInteger(lp,numfields);
     for (int i = 0; i < numfields; i++) {