diff --git a/.circleci/config.yml b/.circleci/config.yml
index 0ba41b06..07c0cb88 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -271,7 +271,7 @@ jobs:
           RUST_BACKTRACE: 1
           # XXX: begin_test_transaction doesn't play nice over threaded tests
           RUST_TEST_THREADS: 1
-      - image: cimg/mysql:5.7
+      - image: cimg/mysql:8.0
         auth:
           username: $DOCKER_USER
           password: $DOCKER_PASS
diff --git a/README.md b/README.md
index 4cac825e..42a22cec 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ Mozilla Sync Storage built with [Rust](https://rust-lang.org).
 - pkg-config
 - [Rust stable](https://rustup.rs)
 - python 3.9+
-- MySQL 5.7 (or compatible)
+- MySQL 8.0 (or compatible)
   * libmysqlclient (`brew install mysql` on macOS, `apt install libmysqlclient-dev` on Ubuntu, `apt install libmariadb-dev-compat` on Debian)
 
 Depending on your OS, you may also need to install `libgrpcdev`,
diff --git a/docker-compose.mysql.yaml b/docker-compose.mysql.yaml
index a6c9c9f8..f0fe5e03 100644
--- a/docker-compose.mysql.yaml
+++ b/docker-compose.mysql.yaml
@@ -11,7 +11,7 @@
 version: "3"
 services:
   sync-db:
-    image: docker.io/library/mysql:5.7
+    image: docker.io/library/mysql:8.0
     volumes:
       - sync_db_data:/var/lib/mysql
     restart: always
@@ -32,7 +32,7 @@ services:
       timeout: 2s
 
   tokenserver-db:
-    image: docker.io/library/mysql:5.7
+    image: docker.io/library/mysql:8.0
     volumes:
       - tokenserver_db_data:/var/lib/mysql
     restart: always
diff --git a/docker-compose.spanner.yaml b/docker-compose.spanner.yaml
index 167c6111..72664c0a 100644
--- a/docker-compose.spanner.yaml
+++ b/docker-compose.spanner.yaml
@@ -26,7 +26,7 @@ services:
     environment:
       SYNC_SYNCSTORAGE__SPANNER_EMULATOR_HOST: sync-db:9020
   tokenserver-db:
-    image: docker.io/library/mysql:5.7
+    image: docker.io/library/mysql:8.0
     volumes:
       - tokenserver_db_data:/var/lib/mysql
     restart: always
diff --git a/syncstorage-mysql/src/diesel_ext.rs b/syncstorage-mysql/src/diesel_ext.rs
index 31b29956..7c2214a3 100644
--- a/syncstorage-mysql/src/diesel_ext.rs
+++ b/syncstorage-mysql/src/diesel_ext.rs
@@ -1,43 +1,11 @@
 use diesel::{
     backend::Backend,
     insertable::CanInsertInSingleQuery,
-    mysql::Mysql,
     query_builder::{AstPass, InsertStatement, QueryFragment, QueryId},
-    query_dsl::methods::LockingDsl,
     result::QueryResult,
     Expression, RunQueryDsl, Table,
 };
 
-/// Emit MySQL <= 5.7's `LOCK IN SHARE MODE`
-///
-/// MySQL 8 supports `FOR SHARE` as an alias (which diesel natively supports)
-pub trait LockInShareModeDsl {
-    type Output;
-
-    fn lock_in_share_mode(self) -> Self::Output;
-}
-
-impl<T> LockInShareModeDsl for T
-where
-    T: LockingDsl<LockInShareMode>,
-{
-    type Output = <T as LockingDsl<LockInShareMode>>::Output;
-
-    fn lock_in_share_mode(self) -> Self::Output {
-        self.with_lock(LockInShareMode)
-    }
-}
-
-#[derive(Debug, Clone, Copy, QueryId)]
-pub struct LockInShareMode;
-
-impl QueryFragment<Mysql> for LockInShareMode {
-    fn walk_ast(&self, mut out: AstPass<'_, Mysql>) -> QueryResult<()> {
-        out.push_sql(" LOCK IN SHARE MODE");
-        Ok(())
-    }
-}
-
 #[derive(Debug, Clone)]
 pub struct OnDuplicateKeyUpdate<T, U, Op, Ret, X>(Box<InsertStatement<T, U, Op, Ret>>, X);
 
diff --git a/syncstorage-mysql/src/models.rs b/syncstorage-mysql/src/models.rs
index 5598b479..287692bf 100644
--- a/syncstorage-mysql/src/models.rs
+++ b/syncstorage-mysql/src/models.rs
@@ -25,7 +25,6 @@ use syncstorage_settings::{Quota, DEFAULT_MAX_TOTAL_RECORDS};
 
 use super::{
     batch,
-    diesel_ext::LockInShareModeDsl,
     error::DbError,
     pool::CollectionCache,
     schema::{bso, collections, user_collections},
@@ -178,7 +177,7 @@ impl MysqlDb {
             .select(user_collections::modified)
             .filter(user_collections::user_id.eq(user_id))
             .filter(user_collections::collection_id.eq(collection_id))
-            .lock_in_share_mode()
+            .for_share()
             .first(&self.conn)
             .optional()?;
         if let Some(modified) = modified {