diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 031a8824b1..6745409964 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -402,6 +402,14 @@ def __call__(self, *args, **kwargs):
     def get_request(self, *args, **kwargs):
         return lambda: self(*args, **kwargs)
 
+def arg_to_cli(arg):
+    if isinstance(arg, bool):
+        return str(arg).lower()
+    elif isinstance(arg, dict) or isinstance(arg, list):
+        return json.dumps(arg)
+    else:
+        return str(arg)
+
 class TestNodeCLI():
     """Interface to bitcoin-cli for an individual node"""
 
@@ -433,8 +441,8 @@ def batch(self, requests):
 
     def send_cli(self, command=None, *args, **kwargs):
         """Run bitcoin-cli command. Deserializes returned string as python object."""
-        pos_args = [str(arg).lower() if type(arg) is bool else str(arg) for arg in args]
-        named_args = [str(key) + "=" + str(value) for (key, value) in kwargs.items()]
+        pos_args = [arg_to_cli(arg) for arg in args]
+        named_args = [str(key) + "=" + arg_to_cli(value) for (key, value) in kwargs.items()]
         assert not (pos_args and named_args), "Cannot use positional arguments and named arguments in the same bitcoin-cli call"
         p_args = [self.binary, "-datadir=" + self.datadir] + self.options
         if named_args: