diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d75f8b1bb..b17dfb4806 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ All notable changes to this project will be documented in this file. From versio
 - Fix unexpected results when embedding and filtering the same table more than once by @laurenceisla in #4075
 - Fix connection retrying message in `PGRST000` error by @netqo in #4980
   + Remove redundant "Retrying the connection." from message because it is logged separately
+- Fix request failures when `work_mem` is set on a role by @laurenceisla in #4955
 
 ### Changed
 
diff --git a/src/PostgREST/Config/Database.hs b/src/PostgREST/Config/Database.hs
index 54386016ab..9c97554908 100644
--- a/src/PostgREST/Config/Database.hs
+++ b/src/PostgREST/Config/Database.hs
@@ -16,6 +16,7 @@ import Control.Arrow ((***))
 import PostgREST.Config.PgVersion (PgVersion (..), pgVersion150)
 
 import qualified Data.HashMap.Strict as HM
+import qualified Data.Text           as T
 
 import qualified Hasql.Decoders             as HD
 import qualified Hasql.Encoders             as HE
@@ -32,8 +33,8 @@ type RoleSettings     = (HM.HashMap ByteString (HM.HashMap ByteString ByteString
 type RoleIsolationLvl = HM.HashMap ByteString SQL.IsolationLevel
 type TimezoneNames    = Set Text -- cache timezone names for prefer timezone=
 
-toIsolationLevel :: (Eq a, IsString a) => a -> SQL.IsolationLevel
-toIsolationLevel a = case a of
+toIsolationLevel :: Text -> SQL.IsolationLevel
+toIsolationLevel a = case T.toLower a of
   "repeatable read" -> SQL.RepeatableRead
   "serializable"    -> SQL.Serializable
   _                 -> SQL.ReadCommitted
@@ -148,7 +149,7 @@ queryRoleSettings pgVer =
         SELECT
           rolname,
           substr(setting, 1, strpos(setting, '=') - 1) as key,
-          lower(substr(setting, strpos(setting, '=') + 1)) as value
+          substr(setting, strpos(setting, '=') + 1) as value
         FROM role_setting
       ),
       iso_setting AS (
diff --git a/src/PostgREST/SchemaCache.hs b/src/PostgREST/SchemaCache.hs
index e026dc1456..a487b70089 100644
--- a/src/PostgREST/SchemaCache.hs
+++ b/src/PostgREST/SchemaCache.hs
@@ -461,7 +461,7 @@ funcsSqlQuery = encodeUtf8 [trimming|
     bt.oid <> bt.base_type as rettype_is_composite_alias,
     p.provolatile,
     p.provariadic > 0 as hasvariadic,
-    lower((regexp_split_to_array((regexp_split_to_array(iso_config, '='))[2], ','))[1]) AS transaction_isolation_level,
+    (regexp_split_to_array((regexp_split_to_array(iso_config, '='))[2], ','))[1] AS transaction_isolation_level,
     coalesce(func_settings.kvs, '{}') as kvs
   FROM pg_proc p
   LEFT JOIN arguments a ON a.oid = p.oid
diff --git a/test/io/__snapshots__/test_cli/test_schema_cache_snapshot[dbRoutines].yaml b/test/io/__snapshots__/test_cli/test_schema_cache_snapshot[dbRoutines].yaml
index 7063ea43bb..f6b66bba60 100644
--- a/test/io/__snapshots__/test_cli/test_schema_cache_snapshot[dbRoutines].yaml
+++ b/test/io/__snapshots__/test_cli/test_schema_cache_snapshot[dbRoutines].yaml
@@ -582,6 +582,23 @@
       pdSchema: public
       pdVolatility: Volatile
 
+- - qiName: get_work_mem
+    qiSchema: public
+  - - pdDescription: null
+      pdFuncSettings: []
+      pdHasVariadic: false
+      pdName: get_work_mem
+      pdParams: []
+      pdReturnType:
+        contents:
+          contents:
+            qiName: text
+            qiSchema: pg_catalog
+          tag: Scalar
+        tag: Single
+      pdSchema: public
+      pdVolatility: Volatile
+
 - - qiName: notify_do_nothing
     qiSchema: public
   - - pdDescription: null
diff --git a/test/io/fixtures/roles.sql b/test/io/fixtures/roles.sql
index 61070d7a1e..fbe8d8ac9a 100644
--- a/test/io/fixtures/roles.sql
+++ b/test/io/fixtures/roles.sql
@@ -8,11 +8,12 @@ CREATE ROLE postgrest_test_author;
 CREATE ROLE postgrest_test_serializable;
 CREATE ROLE postgrest_test_repeatable_read;
 CREATE ROLE postgrest_test_w_superuser_settings;
+CREATE ROLE postgrest_test_work_mem;
 
 GRANT
   postgrest_test_anonymous, postgrest_test_author,
   postgrest_test_serializable, postgrest_test_repeatable_read,
-  postgrest_test_w_superuser_settings TO :"PGUSER";
+  postgrest_test_w_superuser_settings, postgrest_test_work_mem TO :"PGUSER";
 
 ALTER ROLE :"PGUSER" SET pgrst.db_anon_role = 'postgrest_test_anonymous';
 ALTER ROLE postgrest_test_serializable SET default_transaction_isolation = 'serializable';
@@ -23,3 +24,5 @@ ALTER ROLE postgrest_test_w_superuser_settings SET log_min_messages = 'fatal';
 
 ALTER ROLE postgrest_test_anonymous SET statement_timeout TO '5s';
 ALTER ROLE postgrest_test_author SET statement_timeout TO '10s';
+
+ALTER ROLE postgrest_test_work_mem SET work_mem TO '3MB';
diff --git a/test/io/fixtures/schema.sql b/test/io/fixtures/schema.sql
index 0ca35079e2..85c1d274a2 100644
--- a/test/io/fixtures/schema.sql
+++ b/test/io/fixtures/schema.sql
@@ -265,3 +265,7 @@ create or replace function custom_vary_hdr() returns void as $$
     perform set_config('response.headers', '[{"Vary": "X-Test-Accept"}]', false);
   end
 $$ language plpgsql;
+
+create or replace function get_work_mem() returns text as $$
+  select current_setting('work_mem', true);
+$$ language sql;
diff --git a/test/io/test_io.py b/test/io/test_io.py
index 6c20c0d0f6..a9a7da03ec 100644
--- a/test/io/test_io.py
+++ b/test/io/test_io.py
@@ -2187,3 +2187,19 @@ def test_positive_pool_metric(defaultenv):
                 ).group(1)
             )
             assert metrics >= 0
+
+
+def test_work_mem_in_role_settings(defaultenv):
+    "Should work when setting work_mem on a role. See https://github.com/PostgREST/postgrest/issues/4955"
+
+    env = {
+        **defaultenv,
+        "PGRST_JWT_SECRET": SECRET,
+    }
+
+    headers = jwtauthheader({"role": "postgrest_test_work_mem"}, SECRET)
+
+    with run(env=env) as postgrest:
+        response = postgrest.session.post("/rpc/get_work_mem", headers=headers)
+        assert response.status_code == 200
+        assert response.text == '"3MB"'