diff --git a/edb/pgsql/metaschema.py b/edb/pgsql/metaschema.py
index 0a696b43072..3152f6a1da8 100644
--- a/edb/pgsql/metaschema.py
+++ b/edb/pgsql/metaschema.py
@@ -8239,6 +8239,26 @@ async def generate_support_functions(
     return trampoline_functions(cmds)
 
 
+async def regenerate_config_support_functions(
+    conn: PGConnection,
+    config_spec: edbconfig.Spec,
+) -> None:
+    # Regenerate functions dependent on config spec.
+    commands = dbops.CommandGroup()
+
+    funcs = [
+        ApplySessionConfigFunction(config_spec),
+        PostgresJsonConfigValueToFrontendConfigValueFunction(config_spec),
+    ]
+
+    cmds = [dbops.CreateFunction(func, or_replace=True) for func in funcs]
+    commands.add_commands(cmds)
+
+    block = dbops.PLTopBlock()
+    commands.generate(block)
+    await _execute_block(conn, block)
+
+
 async def generate_more_support_functions(
     conn: PGConnection,
     compiler: edbcompiler.Compiler,
diff --git a/edb/server/bootstrap.py b/edb/server/bootstrap.py
index e7a526de6f4..7e33d70c66d 100644
--- a/edb/server/bootstrap.py
+++ b/edb/server/bootstrap.py
@@ -1781,8 +1781,10 @@ async def _init_stdlib(
             await conn.sql_execute(testmode_sql.encode("utf-8"))
             trampolines.extend(new_trampolines)
         # _testmode includes extra config settings, so make sure
-        # those are picked up.
+        # those are picked up...
         config_spec = config.load_spec_from_schema(stdlib.stdschema)
+        # ...and that config functions dependent on it are regenerated
+        await metaschema.regenerate_config_support_functions(conn, config_spec)
 
     logger.info('Finalizing database setup...')