diff --git a/src/underworld3/utilities/_params.py b/src/underworld3/utilities/_params.py
index 950c8eb1..e5e81f23 100644
--- a/src/underworld3/utilities/_params.py
+++ b/src/underworld3/utilities/_params.py
@@ -156,6 +156,14 @@ def __init__(self, **defaults):
         object.__setattr__(self, '_values', {})
         object.__setattr__(self, '_sources', {})
 
+        # Ensure command-line options (-uw_*) are loaded into the PETSc options
+        # database BEFORE we read overrides. petsc4py populates this DB from
+        # sys.argv automatically on some platforms but NOT others (e.g. Gadi),
+        # where Params previously fell back silently to the defaults even though
+        # the CLI args were present (issue #111). parse_cmd_line_options() is
+        # idempotent, so this is safe to call on every Params construction.
+        uw.parse_cmd_line_options()
+
         # Use the module-level options object
         opts = uw.options
 
diff --git a/tests/test_0821_params_cli_override.py b/tests/test_0821_params_cli_override.py
new file mode 100644
index 00000000..7f46e2a1
--- /dev/null
+++ b/tests/test_0821_params_cli_override.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+"""Regression: uw.Params picks up -uw_* command-line overrides (#111).
+
+On some platforms (e.g. Gadi) petsc4py does NOT auto-populate the PETSc options
+database from sys.argv, so uw.Params silently fell back to its defaults even
+when the CLI argument was present. Params now calls parse_cmd_line_options()
+during construction, so a `-uw_<name> <value>` override is applied regardless of
+platform.
+"""
+import sys
+
+import pytest
+
+import underworld3 as uw
+
+pytestmark = [pytest.mark.level_1, pytest.mark.tier_a]
+
+
+def _clear(name):
+    from petsc4py import PETSc
+
+    opts = PETSc.Options()
+    if opts.hasName(name):
+        opts.delValue(name)
+
+
+def test_params_applies_cli_override():
+    """A -uw_* CLI argument overrides the Params default even when the options
+    DB was not pre-populated (the Gadi failure mode in #111)."""
+    saved = sys.argv
+    try:
+        # Simulate Gadi: CLI arg present, options DB not yet populated.
+        _clear("uw_cellsize")
+        sys.argv = ["prog", "-uw_cellsize", "1/16"]
+        params = uw.Params(uw_cellsize=uw.Param("1/8", type=uw.ParamType.STRING))
+        assert params.uw_cellsize == "1/16", (
+            f"CLI override not applied: got {params.uw_cellsize!r}, expected '1/16'"
+        )
+    finally:
+        sys.argv = saved
+        _clear("uw_cellsize")
+
+
+def test_params_uses_default_without_cli():
+    """With no CLI override, Params returns its default."""
+    saved = sys.argv
+    try:
+        _clear("uw_testparam_111")
+        sys.argv = ["prog"]
+        params = uw.Params(uw_testparam_111=uw.Param("default_value", type=uw.ParamType.STRING))
+        assert params.uw_testparam_111 == "default_value"
+    finally:
+        sys.argv = saved