diff --git a/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/ExperimentImportHelper.java b/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/ExperimentImportHelper.java
index fadb1a59580939688d8ce10476c2a4f56bbfb071..e8cf96052595159271d559ae22e47b05f9da723e 100644
--- a/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/ExperimentImportHelper.java
+++ b/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/ExperimentImportHelper.java
@@ -167,9 +167,9 @@ public class ExperimentImportHelper extends BasicImportHelper
             if (!attributeValidator.isHeader(key))
             {
                 String value = getValueByColumnName(header, values, key);
-                if (value != null && value.isEmpty()) { // Skip empty values to avoid deleting by mistake
+                if (value == null || value.isEmpty()) { // Skip empty values to avoid deleting by mistake
                     continue;
-                } else if (value != null && (value.equals("--DELETE--") || value.equals("__DELETE__"))) // Do explicit delete
+                } else if (value.equals("--DELETE--") || value.equals("__DELETE__")) // Do explicit delete
                 {
                     value = null;
                 } else { // Normal behaviour, set value
diff --git a/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/SampleImportHelper.java b/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/SampleImportHelper.java
index cd4b895351715de2c4db5c9b75eeeaa0df7b3257..79b7bfac0708676c37602cf2e436e6036b793742 100644
--- a/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/SampleImportHelper.java
+++ b/openbis/source/java/ch/ethz/sis/openbis/generic/server/xls/importer/helper/SampleImportHelper.java
@@ -330,9 +330,9 @@ public class SampleImportHelper extends BasicImportHelper
             if (!attributeValidator.isHeader(key))
             {
                 String value = getValueByColumnName(header, values, key);
-                if (value != null && value.isEmpty()) { // Skip empty values to avoid deleting by mistake
+                if (value == null || value.isEmpty()) { // Skip empty values to avoid deleting by mistake
                     continue;
-                } else if (value != null && (value.equals("--DELETE--") || value.equals("__DELETE__"))) // Do explicit delete
+                } else if (value.equals("--DELETE--") || value.equals("__DELETE__")) // Do explicit delete
                 {
                     value = null;
                 } else { // Normal behaviour, set value