diff --git a/plugins/clnrest/utilities/shared.py b/plugins/clnrest/utilities/shared.py
index 3b51369e10ef..f58e0026d2f6 100644
--- a/plugins/clnrest/utilities/shared.py
+++ b/plugins/clnrest/utilities/shared.py
@@ -1,5 +1,6 @@
 import json5
 import ipaddress
+import pyln.client
 
 
 CERTS_PATH, REST_PROTOCOL, REST_HOST, REST_PORT, REST_CSP, REST_CORS_ORIGINS = "", "", "", "", "", []
@@ -64,8 +65,29 @@ def set_config(options):
     return None
 
 
+def convert_millisatoshis(item):
+    """
+    The global JSON encoder has been replaced (see
+    monkey_patch_json!)  by one that turns Millisatoshi class object
+    into strings ending in msat.  We do not want the http response
+    to be encoded like that!  pyln-client should probably not do that,
+    but meanwhile, convert them to integers.
+    """
+    if isinstance(item, dict):
+        ret = {}
+        for k in item:
+            ret[k] = convert_millisatoshis(item[k])
+    elif isinstance(item, list):
+        ret = [convert_millisatoshis(i) for i in item]
+    elif isinstance(item, pyln.client.Millisatoshi):
+        ret = int(item)
+    else:
+        ret = item
+    return ret
+
+
 def call_rpc_method(plugin, rpc_method, payload):
-    return plugin.rpc.call(rpc_method, payload)
+    return convert_millisatoshis(plugin.rpc.call(rpc_method, payload))
 
 
 def verify_rune(plugin, rune, rpc_method, rpc_params):
diff --git a/tests/test_clnrest.py b/tests/test_clnrest.py
index 4a9e66979a07..fedf42166862 100644
--- a/tests/test_clnrest.py
+++ b/tests/test_clnrest.py
@@ -237,6 +237,28 @@ def test_clnrest_rpc_method(node_factory):
     assert 'bolt11' in response.json()
 
 
+def test_clnrest_large_response(node_factory):
+    """Test a large reply still works (and msat fields are integers!)"""
+    # start a node with clnrest
+    l1, base_url, ca_cert = start_node_with_clnrest(node_factory)
+    http_session = http_session_with_retry()
+
+    # Add 500 invoices, test list
+    NUM_INVOICES = 500
+    for i in range(NUM_INVOICES):
+        l1.rpc.invoice(amount_msat=100, label=str(i), description="inv")
+
+    rune = l1.rpc.createrune()['rune']
+    response = http_session.post(base_url + '/v1/listinvoices', headers={'Rune': rune},
+                                 verify=ca_cert)
+    # No, this doesn't return JSON, it *parses* it into a Python object!
+    resp = response.json()
+
+    # Make sure it hasn't turned msat fields into strings!
+    assert not isinstance(resp['invoices'][0]['amount_msat'], Millisatoshi)
+    assert len(resp['invoices']) == NUM_INVOICES
+
+
 # Tests for websocket are written separately to avoid flake8
 # to complain with the errors F811 like this "F811 redefinition of
 # unused 'message'".