diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/ProjectIdentifier.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/ProjectIdentifier.java
index 4d916cc5c1cd3641c93c2e519c171ceacbd8af81..854f8ad9e9eb625f8a35f83c84d56f65aabe28e3 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/ProjectIdentifier.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/ProjectIdentifier.java
@@ -60,6 +60,11 @@ public class ProjectIdentifier extends SpaceIdentifier
     {
         this.projectCode = projectCode;
     }
+    
+    public String asProjectIdentifierString()
+    {
+        return new ProjectIdentifier(getSpaceCode(), getProjectCode()).toString();
+    }
 
     @Override
     public boolean equals(final Object obj)
diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/SampleOwnerIdentifier.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/SampleOwnerIdentifier.java
index 9cd6dabef7b5a20e211c8338fefffc56b585df02..17de3484743f0162f50290b271e74fe90b7da1fe 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/SampleOwnerIdentifier.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/identifier/SampleOwnerIdentifier.java
@@ -95,7 +95,7 @@ public class SampleOwnerIdentifier extends AbstractHashable implements Serializa
     {
         if (isProjectLevel())
         {
-            return projectIdentifier.toString() + Constants.IDENTIFIER_SEPARATOR;
+            return projectIdentifier.asProjectIdentifierString() + Constants.IDENTIFIER_SEPARATOR;
         } else if (isSpaceLevel())
         {
             if (isInsideHomeSpace())