diff --git a/supervision/detection/utils/iou_and_nms.py b/supervision/detection/utils/iou_and_nms.py
index 1a6f80bc5..1eccd34b1 100644
--- a/supervision/detection/utils/iou_and_nms.py
+++ b/supervision/detection/utils/iou_and_nms.py
@@ -72,7 +72,7 @@ def from_value(cls, value: OverlapMetric | str) -> OverlapMetric:
         if isinstance(value, cls):
             return value
         if isinstance(value, str):
-            value = value.lower()
+            value = value.upper()
             try:
                 return cls(value)
             except ValueError: