diff --git a/drools-compiler/src/main/java/org/drools/rule/builder/RuleBuilder.java b/drools-compiler/src/main/java/org/drools/rule/builder/RuleBuilder.java
index <HASH>..<HASH> 100644
--- a/drools-compiler/src/main/java/org/drools/rule/builder/RuleBuilder.java
+++ b/drools-compiler/src/main/java/org/drools/rule/builder/RuleBuilder.java
@@ -382,6 +382,8 @@ public class RuleBuilder {
             MVELObjectExpression period = null;
             if ( tok.hasMoreTokens() ) {
                 period = MVELObjectExpressionBuilder.build( tok.nextToken().trim(), context );
+            } else {
+                period = MVELObjectExpressionBuilder.build( "0", context );
             }
 
             timer = new ExpressionIntervalTimer( startDate, endDate, repeatLimit, times, period );
[JBRULES-<I>] fix variable expressions in interval-based timer with delay and no period