diff --git a/common/source/java/ch/systemsx/cisd/common/utilities/StringUtilities.java b/common/source/java/ch/systemsx/cisd/common/utilities/StringUtilities.java
index d24ce0c67e5870dfcddaba940af2201faaf64759..4f6eec532b856285b34e560a4f7f770e02f599d5 100644
--- a/common/source/java/ch/systemsx/cisd/common/utilities/StringUtilities.java
+++ b/common/source/java/ch/systemsx/cisd/common/utilities/StringUtilities.java
@@ -117,9 +117,7 @@ public final class StringUtilities
      */
     public static String capitalize(String string)
     {
-        assert string != null;
-
-        if (string.length() == 0) // Guard: empty string.
+        if (StringUtils.isBlank(string))
         {
             return string;
         }