diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e9ccd0..67fc031 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 ## 0.6.0 (unreleased)
 
+If upgrading with Postgres < 13, see [this note](https://github.com/pgvector/pgvector#060).
+
+- Changed storage for vector from `extended` to `external`
 - Improved performance of HNSW
 - Added support for parallel index builds for HNSW
 - Added validation for GUC parameters
diff --git a/README.md b/README.md
index ba96702..7143ce1 100644
--- a/README.md
+++ b/README.md
@@ -729,6 +729,16 @@ SELECT extversion FROM pg_extension WHERE extname = 'vector';
 
 ## Upgrade Notes
 
+### 0.6.0 [unreleased]
+
+If upgrading with Postgres < 13, remove this line from `sql/vector--0.5.1--0.6.0.sql`:
+
+```sql
+ALTER TYPE vector SET (STORAGE = external);
+```
+
+Then run `make install` and `ALTER EXTENSION vector UPDATE;`.
+
 ### 0.4.0
 
 If upgrading with Postgres < 13, remove this line from `sql/vector--0.3.2--0.4.0.sql`:
diff --git a/sql/vector--0.5.1--0.6.0.sql b/sql/vector--0.5.1--0.6.0.sql
new file mode 100644
index 0000000..8e5af7f
--- /dev/null
+++ b/sql/vector--0.5.1--0.6.0.sql
@@ -0,0 +1,5 @@
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION vector UPDATE TO '0.6.0'" to load this file. \quit
+
+-- remove this single line for Postgres < 13
+ALTER TYPE vector SET (STORAGE = external);
diff --git a/sql/vector.sql b/sql/vector.sql
index 137931f..4b17faa 100644
--- a/sql/vector.sql
+++ b/sql/vector.sql
@@ -26,7 +26,7 @@ CREATE TYPE vector (
 	TYPMOD_IN = vector_typmod_in,
 	RECEIVE   = vector_recv,
 	SEND      = vector_send,
-	STORAGE   = extended
+	STORAGE   = external
 );
 
 -- functions