diff --git a/mcoplib/profiler.py b/mcoplib/profiler.py
index adfba41..8b319aa 100644
--- a/mcoplib/profiler.py
+++ b/mcoplib/profiler.py
@@ -6,13 +6,10 @@
 
 def _is_profiler_enabled() -> bool:
     """
-    Env switch: PROFILER_ENABLED==0 -> disabled, else enabled.
+    Env switch: PROFILER_ENABLED=false/0/off/no -> disabled, else enabled.
     """
     v = os.getenv("PROFILER_ENABLED", "1")
-    try:
-        return not (str(v).strip() == "0")
-    except Exception:
-        return True
+    return v.strip().lower() not in {"0", "false", "off", "no"}
 
 
 def _timestamp() -> str:
diff --git a/unit_test/test_profiler_env.py b/unit_test/test_profiler_env.py
new file mode 100644
index 0000000..343bf4a
--- /dev/null
+++ b/unit_test/test_profiler_env.py
@@ -0,0 +1,12 @@
+from mcoplib.profiler import _is_profiler_enabled
+
+
+def test_profiler_disabled_by_common_false_values(monkeypatch):
+    for value in ("0", "false", "False", "off", "NO"):
+        monkeypatch.setenv("PROFILER_ENABLED", value)
+        assert not _is_profiler_enabled()
+
+
+def test_profiler_enabled_by_default(monkeypatch):
+    monkeypatch.delenv("PROFILER_ENABLED", raising=False)
+    assert _is_profiler_enabled()