diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/SampleType.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/SampleType.java
index e149bca6021edc9b73a33f9b6d78d63a7dc91901..12d60481230920c003d1eda72fd6254e088951ab 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/SampleType.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/SampleType.java
@@ -45,7 +45,8 @@ public final class SampleType extends EntityType implements IsSerializable
 
     private boolean listable;
 
-    private List<SampleTypePropertyType> sampleTypePropertyTypes;
+    private List<SampleTypePropertyType> sampleTypePropertyTypes =
+            new ArrayList<SampleTypePropertyType>(0);
 
     public final boolean isDefinedInFileSampleTypeCode()
     {