diff --git a/src/main/java/it/cavallium/data/generator/SourcesGenerator.java b/src/main/java/it/cavallium/data/generator/SourcesGenerator.java
index 5a49b31..f97545f 100644
--- a/src/main/java/it/cavallium/data/generator/SourcesGenerator.java
+++ b/src/main/java/it/cavallium/data/generator/SourcesGenerator.java
@@ -1373,11 +1373,15 @@ public class SourcesGenerator {
 														return fieldName;
 													}
 											);
+											deserializeMethod.beginControlFlow("");
 											deserializeMethod.addStatement(
-													"$$field$$" + (currentVarNumber.getInt(upgradeDataTransformation.from) + 1) + "$$"
-															+ upgradeDataTransformation.from + " = ($T) " + dataUpgraderFieldName + ".upgrade(($T) $$field$$"
+													"$T upgraded = ($T) " + dataUpgraderFieldName + ".upgrade(($T) $$field$$"
 															+ currentVarNumber.getInt(upgradeDataTransformation.from) + "$$"
 															+ upgradeDataTransformation.from + ")", toType, toTypeBoxed, fromTypeBoxed);
+											deserializeMethod.addStatement(
+													"$$field$$" + (currentVarNumber.getInt(upgradeDataTransformation.from) + 1) + "$$"
+															+ upgradeDataTransformation.from + " = upgraded");
+											deserializeMethod.endControlFlow();
 											Objects.requireNonNull(currentTransformedFieldTypes.remove(
 													upgradeDataTransformation.transformClass + "." + upgradeDataTransformation.from));
 											currentTransformedFieldTypes.put(