diff --git a/misc/python/materialize/zippy/mz_actions.py b/misc/python/materialize/zippy/mz_actions.py
index 782d980e886e8..03389996dab7d 100644
--- a/misc/python/materialize/zippy/mz_actions.py
+++ b/misc/python/materialize/zippy/mz_actions.py
@@ -8,6 +8,8 @@
 # by the Apache License, Version 2.0.
 
 
+import os
+
 from materialize.mzcompose.composition import Composition
 from materialize.mzcompose.services.materialized import (
     LEADER_STATUS_HEALTHCHECK,
@@ -70,7 +72,21 @@ def __init__(
         capabilities: Capabilities,
         additional_system_parameter_defaults: dict[str, str] = {},
     ) -> None:
-        self.additional_system_parameter_defaults = additional_system_parameter_defaults
+        if additional_system_parameter_defaults:
+            self.additional_system_parameter_defaults = (
+                additional_system_parameter_defaults
+            )
+        else:
+            self.additional_system_parameter_defaults = {}
+            system_parameter_default = os.getenv("CI_MZ_SYSTEM_PARAMETER_DEFAULT", "")
+            if system_parameter_default:
+                for val in system_parameter_default.split(";"):
+                    x = val.split("=", maxsplit=1)
+                    assert (
+                        len(x) == 2
+                    ), f"CI_MZ_SYSTEM_PARAMETER_DEFAULT '{val}' should be the format <key>=<val>"
+                    self.additional_system_parameter_defaults[x[0]] = x[1]
+
         super().__init__(capabilities)
 
     def run(self, c: Composition, state: State) -> None:
diff --git a/test/zippy/mzcompose.py b/test/zippy/mzcompose.py
index 70f4efdd6736d..23a5f7e434e6e 100644
--- a/test/zippy/mzcompose.py
+++ b/test/zippy/mzcompose.py
@@ -13,6 +13,7 @@
 expected state it can verify results for correctness.
 """
 
+import os
 import random
 import re
 import time
@@ -177,14 +178,6 @@ def workflow_default(c: Composition, parser: WorkflowArgumentParser) -> None:
         help="Start Prometheus and Grafana",
     )
 
-    parser.add_argument(
-        "--system-param",
-        type=str,
-        action="append",
-        nargs="*",
-        help="System parameters to set in Materialize, i.e. what you would set with `ALTER SYSTEM SET`",
-    )
-
     parser.add_argument(
         "--azurite", action="store_true", help="Use Azurite as blob store instead of S3"
     )
@@ -215,10 +208,14 @@ def workflow_default(c: Composition, parser: WorkflowArgumentParser) -> None:
     random.seed(args.seed)
 
     additional_system_parameter_defaults = {}
-    for val in args.system_param or []:
-        x = val[0].split("=", maxsplit=1)
-        assert len(x) == 2, f"--system-param '{val}' should be the format <key>=<val>"
-        additional_system_parameter_defaults[x[0]] = x[1]
+    system_parameter_default = os.getenv("CI_MZ_SYSTEM_PARAMETER_DEFAULT", "")
+    if system_parameter_default:
+        for val in system_parameter_default.split(";"):
+            x = val.split("=", maxsplit=1)
+            assert (
+                len(x) == 2
+            ), f"CI_MZ_SYSTEM_PARAMETER_DEFAULT '{val}' should be the format <key>=<val>"
+            additional_system_parameter_defaults[x[0]] = x[1]
 
     with c.override(
         Cockroach(