diff --git a/src/java/com/samskivert/servlet/util/ParameterUtil.java b/src/java/com/samskivert/servlet/util/ParameterUtil.java
index 20c28d69..a6cf4a84 100644
--- a/src/java/com/samskivert/servlet/util/ParameterUtil.java
+++ b/src/java/com/samskivert/servlet/util/ParameterUtil.java
@@ -378,7 +378,9 @@ public class ParameterUtil
 	throws DataValidationException
     {
 	try {
-            return _dparser.parse(value);
+            synchronized (_dparser) {
+                return _dparser.parse(value);
+            }
 	} catch (ParseException pe) {
 	    throw new DataValidationException(invalidDataMessage);
 	}