diff --git a/api/onnx_web/upscale.py b/api/onnx_web/upscale.py
index 8d9c470c3..66cdda267 100644
--- a/api/onnx_web/upscale.py
+++ b/api/onnx_web/upscale.py
@@ -39,7 +39,7 @@ def float(self):
     def cpu(self):
         return self
 
-    def clamp(self, min, max):
+    def clamp_(self, min, max):
         self.source = np.clip(self.source, min, max)
 
     def numpy(self):