diff --git a/js/src/jstracer.cpp b/js/src/jstracer.cpp
index 12584146b7e..cb47af3d3fc 100644
--- a/js/src/jstracer.cpp
+++ b/js/src/jstracer.cpp
@@ -268,6 +268,13 @@ Oracle::isStackSlotUndemotable(JSScript* script, jsbytecode* ip, unsigned slot)
     return _dontDemote.get(hash);
 }
 
+/* Clear the oracle. */
+void
+Oracle::clear()
+{
+    _dontDemote.reset();
+}
+
 static LIns* demote(LirWriter *out, LInsp i)
 {
     if (i->isCall())
diff --git a/js/src/jstracer.h b/js/src/jstracer.h
index 01cf4f0a3d1..1a886df8236 100644
--- a/js/src/jstracer.h
+++ b/js/src/jstracer.h
@@ -165,6 +165,7 @@ public:
     bool isGlobalSlotUndemotable(JSScript* script, unsigned slot) const;
     void markStackSlotUndemotable(JSScript* script, jsbytecode* ip, unsigned slot);
     bool isStackSlotUndemotable(JSScript* script, jsbytecode* ip, unsigned slot) const;
+    void clear();
 };
 
 typedef Queue<uint16> SlotList;