NPE trying to fire a named consequence defined in a parent rule

Trying to fire a named consequence defined in a parent rule the following NPE is thrown

java.lang.NullPointerException
at org.drools.core.definitions.rule.impl.RuleImpl.getNamedConsequence(RuleImpl.java:638)
at org.drools.core.reteoo.RuleTerminalNodeLeftTuple.getConsequence(RuleTerminalNodeLeftTuple.java:165)
at org.drools.core.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1046)