diff --git a/studio/backend/core/inference/diffusion_speed.py b/studio/backend/core/inference/diffusion_speed.py
index 8c2524dfda..52ace4d30a 100644
--- a/studio/backend/core/inference/diffusion_speed.py
+++ b/studio/backend/core/inference/diffusion_speed.py
@@ -374,7 +374,7 @@ def _enable_fp16_accumulation(
     process-wide flag to its prior value on unload."""
     import os
 
-    if os.environ.get("UNSLOTH_DISABLE_FP16_ACCUM", "").strip() in ("1", "true", "yes"):
+    if os.environ.get("UNSLOTH_DISABLE_FP16_ACCUM", "").strip().lower() in ("1", "true", "yes", "on"):
         return False
     name = str(getattr(family, "name", family or "")).lower()
     if name in _FP16_ACCUM_DENY:
diff --git a/studio/backend/tests/test_diffusion_speed.py b/studio/backend/tests/test_diffusion_speed.py
index 9a18090e36..e6ce77116e 100644
--- a/studio/backend/tests/test_diffusion_speed.py
+++ b/studio/backend/tests/test_diffusion_speed.py
@@ -427,6 +427,20 @@ def test_fp16_accum_respects_kill_switch(monkeypatch):
     assert applied["fp16_accum"] is False
 
 
+@pytest.mark.parametrize("value", ["TRUE", "Yes", "On", " true "])
+def test_fp16_accum_kill_switch_is_case_insensitive(monkeypatch, value):
+    # The documented safety escape hatch must honor the common boolean spellings, not only
+    # lowercase "1"/"true"/"yes": an operator setting UNSLOTH_DISABLE_FP16_ACCUM=TRUE to stop
+    # fp16-accumulation drift would otherwise be silently ignored.
+    _stub_torch_fp16_accum(monkeypatch, consumer = True)
+    _stub_gguf_accel(monkeypatch)
+    monkeypatch.setenv("UNSLOTH_DISABLE_FP16_ACCUM", value)
+    applied = apply_speed_optims(
+        _Pipe(), _target(), is_gguf = True, family = _family(), speed_mode = "default"
+    )
+    assert applied["fp16_accum"] is False
+
+
 def test_fp16_accum_respects_family_deny_list(monkeypatch):
     _stub_torch_fp16_accum(monkeypatch, consumer = True)
     _stub_gguf_accel(monkeypatch)