diff --git a/sql/upgrades/152.sql b/sql/upgrades/152.sql
new file mode 100644
--- /dev/null
+++ b/sql/upgrades/152.sql
@@ -0,0 +1,11 @@
+-- SWH DB schema upgrade
+-- from_version: 151
+-- to_version: 152
+-- description: Make content.blake2s256 not null
+
+-- latest schema version
+insert into dbversion(version, release, description)
+      values(152, now(), 'Work In Progress');
+
+alter table content
+    alter column blake2s256 not null;
diff --git a/swh/storage/sql/30-swh-schema.sql b/swh/storage/sql/30-swh-schema.sql
--- a/swh/storage/sql/30-swh-schema.sql
+++ b/swh/storage/sql/30-swh-schema.sql
@@ -17,7 +17,7 @@
 
 -- latest schema version
 insert into dbversion(version, release, description)
-      values(151, now(), 'Work In Progress');
+      values(152, now(), 'Work In Progress');
 
 -- a SHA1 checksum
 create domain sha1 as bytea check (length(value) = 20);
@@ -47,7 +47,7 @@
   sha1       sha1 not null,
   sha1_git   sha1_git not null,
   sha256     sha256 not null,
-  blake2s256 blake2s256,
+  blake2s256 blake2s256 not null,
   length     bigint not null,
   ctime      timestamptz not null default now(),
              -- creation time, i.e. time of (first) injection into the storage