diff --git a/src/main/org/apache/tools/ant/types/FilterSet.java b/src/main/org/apache/tools/ant/types/FilterSet.java
index 6c7789bb4..c248b976a 100644
--- a/src/main/org/apache/tools/ant/types/FilterSet.java
+++ b/src/main/org/apache/tools/ant/types/FilterSet.java
@@ -209,7 +209,7 @@ public class FilterSet extends DataType implements Cloneable {
      */
     public Hashtable getFilterHash() {
         int filterSize = getFilters().size();
-        Hashtable filterHash = new Hashtable(filterSize);
+        Hashtable filterHash = new Hashtable(filterSize + 1);
         for (Enumeration e = getFilters().elements(); e.hasMoreElements();) {
            Filter filter = (Filter) e.nextElement();
            filterHash.put(filter.getToken(), filter.getValue());