diff --git a/doc/FAQ b/doc/FAQ
index fae3bbe9a57..91d441d583e 100644
--- a/doc/FAQ
+++ b/doc/FAQ
@@ -900,6 +900,10 @@ BYTEA           bytea           variable-length array of bytes
         DELETE FROM new;
         COPY new WITH OIDS FROM '/tmp/pgtable';
 
+   OIDs are stored as 4-byte integers, and will overflow at 4 billion. No
+   one has reported this every happening, and we plan to have the limit
+   removed before anyone does.
+   
    TIDs are used to identify specific physical rows with block and offset
    values. Tids change after rows are modified or reloaded. They are used
    by index entries to point to physical rows.
diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html
index 8206819c631..ea94fb6410c 100644
--- a/doc/src/FAQ/FAQ.html
+++ b/doc/src/FAQ/FAQ.html
@@ -1095,6 +1095,10 @@ no reason you can't do it:
 -->
 </PRE><P>
 
+O<small>ID</small>s are stored as 4-byte integers, and will overflow
+at 4 billion. No one has reported this every happening, and we plan to
+have the limit removed before anyone does.<P>
+
 T<small>ID</small>s are used to identify specific physical rows with block and offset
 values.  Tids change after rows are modified or reloaded.  They are used
 by index entries to point to physical rows.<P>