diff --git a/src/heap.cpp b/src/heap.cpp
index b3f7eea200..4b7703aacc 100644
--- a/src/heap.cpp
+++ b/src/heap.cpp
@@ -509,6 +509,9 @@ class Context {
     lowMemoryThreshold(limit / 2),
     lock(0),
 
+    immortalHeapStart(0),
+    immortalHeapEnd(0),
+
     ageMap(&gen1, max(1, log(TenureThreshold)), 1, 0, false),
     gen1(this, &ageMap, 0, 0),
 
@@ -577,6 +580,9 @@ class Context {
   unsigned lowMemoryThreshold;
 
   System::Mutex* lock;
+
+  void* immortalHeapStart;
+  void* immortalHeapEnd;
   
   Segment::Map ageMap;
   Segment gen1;
@@ -948,7 +954,9 @@ update3(Context* c, void* o, bool* needsVisit)
 void*
 update2(Context* c, void* o, bool* needsVisit)
 {
-  if (c->mode == Heap::MinorCollection and c->gen2.contains(o)) {
+  if ((o < c->immortalHeapEnd and o > c->immortalHeapStart)
+      or (c->mode == Heap::MinorCollection and c->gen2.contains(o)))
+  {
     *needsVisit = false;
     return o;
   }
@@ -1669,6 +1677,11 @@ class MyHeap: public Heap {
     c.client = client;
   }
 
+  virtual void setImmortalHeap(uintptr_t* start, unsigned sizeInWords) {
+    c.immortalHeapStart = start;
+    c.immortalHeapEnd = start + sizeInWords;
+  }
+
   virtual void* tryAllocate(unsigned size) {
     return ::tryAllocate(&c, size);
   }
@@ -1698,8 +1711,9 @@ class MyHeap: public Heap {
             Fixie(sizeInWords, objectMask, &(c.fixies), false))->body();
   }
 
-  virtual void* allocateImmortal(Allocator* allocator, unsigned sizeInWords,
-                                 bool objectMask, unsigned* totalInBytes)
+  virtual void* allocateImmortalFixed(Allocator* allocator,
+                                      unsigned sizeInWords, bool objectMask,
+                                      unsigned* totalInBytes)
   {
     *totalInBytes = Fixie::totalSize(sizeInWords, objectMask);
     return (new (allocator->allocate(*totalInBytes))
diff --git a/src/heap.h b/src/heap.h
index bc8f9a5a1c..28f1533d8f 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -52,11 +52,13 @@ class Heap: public Allocator {
   };
 
   virtual void setClient(Client* client) = 0;
+  virtual void setImmortalHeap(uintptr_t* start, unsigned sizeInWords) = 0;
   virtual void collect(CollectionType type, unsigned footprint) = 0;
   virtual void* allocateFixed(Allocator* allocator, unsigned sizeInWords,
                               bool objectMask, unsigned* totalInBytes) = 0;
-  virtual void* allocateImmortal(Allocator* allocator, unsigned sizeInWords,
-                                 bool objectMask, unsigned* totalInBytes) = 0;
+  virtual void* allocateImmortalFixed(Allocator* allocator,
+                                      unsigned sizeInWords, bool objectMask,
+                                      unsigned* totalInBytes) = 0;
   virtual bool needsMark(void* p) = 0;
   virtual bool needsMark(void* p, unsigned offset) = 0;
   virtual void mark(void* p, unsigned offset, unsigned count) = 0;
diff --git a/src/machine.cpp b/src/machine.cpp
index 78a0063995..4d0df1861f 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -1512,6 +1512,8 @@ boot(Thread* t, BootImage* image)
     (heapMapSize(image->heapSize), BytesPerWord);
   uintptr_t* heap = heapMap + heapMapSizeInWords;
   
+  t->m->heap->setImmortalHeap(heap, image->heapSize);
+
   for (unsigned word = 0; word < heapMapSizeInWords; ++word) {
     uintptr_t w = heapMap[word];
     if (w) {
@@ -2170,7 +2172,7 @@ allocate3(Thread* t, Allocator* allocator, Machine::AllocationType type,
   case Machine::ImmortalAllocation: {
     unsigned total;
     object o = static_cast<object>
-      (t->m->heap->allocateImmortal
+      (t->m->heap->allocateImmortalFixed
        (allocator, ceiling(sizeInBytes, BytesPerWord), objectMask, &total));
 
     cast<uintptr_t>(o, 0) = FixedMark;