diff --git a/common/source/java/ch/systemsx/cisd/common/spring/WhiteListCodebaseAwareObjectInputStream.java b/common/source/java/ch/systemsx/cisd/common/spring/WhiteListCodebaseAwareObjectInputStream.java
index 08c70f4cfb06401013fa63928863cd8f8dcc3678..342b9e90c93a089ef9d3a60ec95b7d1dce4cc332 100644
--- a/common/source/java/ch/systemsx/cisd/common/spring/WhiteListCodebaseAwareObjectInputStream.java
+++ b/common/source/java/ch/systemsx/cisd/common/spring/WhiteListCodebaseAwareObjectInputStream.java
@@ -39,7 +39,7 @@ public class WhiteListCodebaseAwareObjectInputStream extends CodebaseAwareObject
 
     private static final List<Pattern> whiteListPatterns = new LinkedList<>();
 
-    {
+    static {
         addToWhiteListPatterns("byte");
         addToWhiteListPatterns("short");
         addToWhiteListPatterns("int");