diff --git a/tests/tools/test_exec_platform.py b/tests/tools/test_exec_platform.py
index e9922d2b..47f872eb 100644
--- a/tests/tools/test_exec_platform.py
+++ b/tests/tools/test_exec_platform.py
@@ -165,6 +165,7 @@ class TestPathAppendPlatform:
 
         with (
             patch ("nanobot.agent.tools.shell._IS_WINDOWS", False),
+            patch ("nanobot.agent.tools.shell.os.pathsep", ":"),
             patch.object (ExecTool, "_spawn", side_effect=capture_spawn),
             patch.object (ExecTool, "_guard_command", return_value=None),
         ):