I have a fact that a Map of Strings: private Map<String,String> property = new HashMap<String,String>(); /** * Gets the property map * @return The property map */ public Map<String, String> getProperty() { return property; } /** * Sets the property map * @param property The new property map */ public void setProperty(Map<String, String> property) { this.property = property; } Inside a rule, I am trying to use this map and the rule looks like: rule "3-new Notificationcp9145Authentication" when notification : Notificationcp9145Authentication($againstId : targetID, $badHostString : badHostString, $applicationName : applicationName) not AlarmEventFact(type == AlarmType.ACTIVE, alarmName == "cp9145Authentication", againstId == $againstId, property['badHostString'] == $badHostString, property['applicationName'] == $applicationName ) then alarmEventKnowledge.create(drools, notification, "cp9145Authentication", new Pair("badHostString", $badHostString), new Pair("applicationName", $applicationName)); end The problem that I am having is that the result of the lookup of "property['badHostString']" is a string that looks like "192.168.1.19" (an IP address). The "badHostString" property of the Notificationcp9145Authentication fact is a String. I am getting an error when the rule is fired. It appears that the "property['badHostString']" is trying to be interpreted as a number. Here is some of the stack traceback: Caused by: java.lang.NumberFormatException at java.math.BigDecimal.<init>(BigDecimal.java:362) at java.math.BigDecimal.<init>(BigDecimal.java:647) at org.mvel.math.IEEEFloatingPointMath.getBigDecimalFromType(IEEEFloatingPointMath.java:373) at org.mvel.math.IEEEFloatingPointMath._doOperations(IEEEFloatingPointMath.java:83) at org.mvel.math.IEEEFloatingPointMath.doOperation(IEEEFloatingPointMath.java:40) at org.mvel.util.ParseTools.doOperations(ParseTools.java:753) at org.mvel.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:20) at org.mvel.MVELRuntime.execute(MVELRuntime.java:87) at org.mvel.CompiledExpression.getValue(CompiledExpression.java:98) at org.mvel.MVEL.executeExpression(MVEL.java:202) at org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:36) at org.drools.rule.PredicateConstraint.isAllowedCachedLeft(PredicateConstraint.java:206) If I change the property value to be something like "abc" then this does not occur, so I am pretty user that it is trying to convert "192.168.1.19" to a number even though it is already a string and the $badHostString is a String as well. How can I force this to not try to convert? Any help will be greatly appreciated.