diff --git a/server/protocol/protocol.py b/server/protocol/protocol.py
index e0f73d963..f8a78cb90 100644
--- a/server/protocol/protocol.py
+++ b/server/protocol/protocol.py
@@ -14,13 +14,21 @@ class CustomJSONEncoder(json.JSONEncoder):
     # taken from https://stackoverflow.com/a/60243503
     def encode(self, o):
         if isinstance(o, Mapping):
-            dict_content = ", ".join(
-                f"{self.encode(key)}: {self.encode(value)}"
-                for (key, value) in o.items()
-            )
-            return '{' + dict_content + '}'
+            # keys must be str, int, float, bool or None
+            dict_content = []
+            for key, value in o.items():
+                # do not use precision for float dict keys
+                if (isinstance(key, int) or isinstance(key, float)):
+                    new_key = f'"{key}"'.lower()
+                elif key is None:
+                    new_key = '"null"'
+                else:
+                    new_key = self.encode(key)
+                new_value = self.encode(value)
+                dict_content.append(f"{new_key}:{new_value}")
+            return "{" + ",".join(dict_content) + "}"
         elif isinstance(o, Iterable) and not isinstance(o, str):
-            return "[" + ", ".join(map(self.encode, o)) + "]"
+            return "[" + ",".join(map(self.encode, o)) + "]"
         elif isinstance(o, float):
             return f"{o:.{config.JSON_FLOAT_DIGITS_PRECISION}f}"
         else:
diff --git a/tests/unit_tests/test_protocol.py b/tests/unit_tests/test_protocol.py
index aa4a72aa5..23c0ccd16 100644
--- a/tests/unit_tests/test_protocol.py
+++ b/tests/unit_tests/test_protocol.py
@@ -265,14 +265,15 @@ def test_json_encoder_float_serialization():
     assert json_encoder.encode(123.0) == '123.00'
     assert json_encoder.encode(0.99) == '0.99'
     assert json_encoder.encode(0.999) == '1.00'
-    assert json_encoder.encode('simple words') == '"simple words"'
-    assert json_encoder.encode([1, 2, 3]) == '[1, 2, 3]'
-    assert json_encoder.encode({'a': 1}) == '{"a": 1}'
 
-    # Check that we did not brake the original behaviour of other things
+
+def test_json_encoder_encodes_server_messages():
+    new_encode = json_encoder.encode
+    old_encode = json.JSONEncoder(separators=(",", ":")).encode
+
     delta_ladder, delta_tmm = 200.3654233558, 19.879223123
 
-    info_dict = {
+    matchmaker_info_dict = {
         "command": "matchmaker_info",
         "queues": [
             {
@@ -300,13 +301,68 @@ def test_json_encoder_float_serialization():
         ]
     }
 
-    expected_info_dict = copy.deepcopy(info_dict)
+    expected_matchmaker_info_dict = copy.deepcopy(matchmaker_info_dict)
 
-    for queue in expected_info_dict["queues"]:
+    for queue in expected_matchmaker_info_dict["queues"]:
         queue["queue_pop_time_delta"] = round(
             queue["queue_pop_time_delta"], config.JSON_FLOAT_DIGITS_PRECISION,
         )
 
-    assert json_encoder.encode(info_dict) == (
-        json.JSONEncoder().encode(expected_info_dict)
+    assert new_encode(matchmaker_info_dict) == (
+        old_encode(expected_matchmaker_info_dict)
     )
+
+    game_info_dict = {
+        "command": "game_info",
+        "visibility": "public",
+        "password_protected": True,
+        "uid": 13,
+        "title": "someone's game",
+        "state": "playing",
+        "game_type": "custom",
+        "featured_mod": "faf",
+        "sim_mods": {},
+        "mapname": "scmp_009",
+        "map_file_path": "maps/scmp_009.zip",
+        "host": "Foo",
+        "num_players": 2,
+        "launched_at": 1111111111.11,
+        "rating_type": "faf",
+        "rating_min": None,
+        "rating_max": None,
+        "enforce_rating_range": False,
+        "team_ids": [
+            {
+                "team_id": 1,
+                "player_ids": [1],
+            },
+        ],
+        "teams": {
+            1: ["Foo"],
+            2: ["Bar"],
+        },
+    }
+    assert new_encode(game_info_dict) == old_encode(game_info_dict)
+
+
+@pytest.mark.parametrize(
+    "dict_key", [True, None, '"double_quoted"', "'single_quoted'", 1, 1.22],
+)
+@pytest.mark.parametrize(
+    "dict_value", [True, None, '"double_quoted"', "'single quoted'", 1, 1.22],
+)
+def test_json_encoder_encodes_dicts(dict_key, dict_value):
+    old_encode = json.JSONEncoder(separators=(",", ":")).encode
+    new_encode = json_encoder.encode
+
+    assert new_encode({dict_key: dict_value}) == (
+        old_encode({dict_key: dict_value})
+    )
+
+
+def test_json_encoder_encodes_lists():
+    old_encode = json.JSONEncoder(separators=(",", ":")).encode
+    new_encode = json_encoder.encode
+
+    weird_list = [True, None, '"double_quoted"', "'single_quoted'", 1, 1.22]
+    assert new_encode(weird_list) == old_encode(weird_list)