diff --git a/CHANGELOGS.md b/CHANGELOGS.md
index 97de28f5c..f249293b0 100644
--- a/CHANGELOGS.md
+++ b/CHANGELOGS.md
@@ -1,12 +1,17 @@
 # Change Logs
 
+## 1.18.1
+
+* Fix np.NAN into np.nan,
+  [#1148](https://github.com/onnx/sklearn-onnx/issues/1148)
+
 ## 1.18.0
 
 * Converter for OneHotEncoder does not add a concat operator if not needed,
-  [#1110](https://github.com/onnx/sklearn-onnx/pull/1110)  
+  [#1110](https://github.com/onnx/sklearn-onnx/pull/1110)
 * Function ``to_onnx`` now forces the main opset to be equal to the
   value speficied by the user (parameter ``target_opset``),
-  [#1109](https://github.com/onnx/sklearn-onnx/pull/1109)  
+  [#1109](https://github.com/onnx/sklearn-onnx/pull/1109)
 * Add converter for TunedThresholdClassifierCV,
   [#1107](https://github.com/onnx/sklearn-onnx/pull/1107)
 
diff --git a/skl2onnx/operator_converters/power_transformer.py b/skl2onnx/operator_converters/power_transformer.py
index 28440a275..c66b063f0 100644
--- a/skl2onnx/operator_converters/power_transformer.py
+++ b/skl2onnx/operator_converters/power_transformer.py
@@ -78,7 +78,7 @@ def convert_powertransformer(
         y_gr0 = OnnxImputer(
             y_gr0,
             imputed_value_floats=[0.0],
-            replaced_value_float=np.NAN,
+            replaced_value_float=getattr(np, "nan", getattr(np, "NAN")),
             op_version=opv,
         )
         y_gr0 = OnnxMul(y_gr0, greater_mask, op_version=opv)
@@ -104,7 +104,7 @@ def convert_powertransformer(
         y_le0 = OnnxImputer(
             y_le0,
             imputed_value_floats=[0.0],
-            replaced_value_float=np.NAN,
+            replaced_value_float=getattr(np, "nan", getattr(np, "NAN")),
             op_version=opv,
         )
         y_le0 = OnnxMul(y_le0, less_mask, op_version=opv)
@@ -130,7 +130,7 @@ def convert_powertransformer(
         y_gr0_l_eq0 = OnnxImputer(
             y_gr0_l_eq0,
             imputed_value_floats=[0.0],
-            replaced_value_float=np.NAN,
+            replaced_value_float=getattr(np, "nan", getattr(np, "NAN")),
             op_version=opv,
         )
         y_gr0_l_eq0 = OnnxMul(y_gr0_l_eq0, lambda_zero_mask, op_version=opv)