diff --git a/mps/code/arena.c b/mps/code/arena.c
index fee56d6378a..e4e7c5e1973 100644
--- a/mps/code/arena.c
+++ b/mps/code/arena.c
@@ -164,7 +164,7 @@ Bool ArenaCheck(Arena arena)
   if (arena->primary != NULL) {
     CHECKD(Chunk, arena->primary);
   }
-  CHECKD_NOSIG(Ring, &arena->chunkRing);
+  CHECKD_NOSIG(Ring, ArenaChunkRing(arena));
   /* Can't use CHECKD_NOSIG because TreeEMPTY is NULL. */
   CHECKL(TreeCheck(ArenaChunkTree(arena)));
   /* TODO: check that the chunkRing and chunkTree have identical members */
@@ -225,7 +225,7 @@ Res ArenaInit(Arena arena, ArenaClass class, Size grainSize, ArgList args)
   arena->zoned = zoned;
 
   arena->primary = NULL;
-  RingInit(&arena->chunkRing);
+  RingInit(ArenaChunkRing(arena));
   arena->chunkTree = TreeEMPTY;
   arena->chunkSerial = (Serial)0;
   
@@ -372,7 +372,7 @@ void ArenaFinish(Arena arena)
   arena->sig = SigInvalid;
   GlobalsFinish(ArenaGlobals(arena));
   LocusFinish(arena);
-  RingFinish(&arena->chunkRing);
+  RingFinish(ArenaChunkRing(arena));
   AVER(ArenaChunkTree(arena) == TreeEMPTY);
 }
 
@@ -587,7 +587,7 @@ Res ArenaDescribeTracts(Arena arena, mps_lib_FILE *stream, Count depth)
   if (stream == NULL)
     return ResFAIL;
 
-  RING_FOR(node, &arena->chunkRing, next) {
+  RING_FOR(node, ArenaChunkRing(arena), next) {
     Chunk chunk = RING_ELT(Chunk, arenaRing, node);
     res = arenaDescribeTractsInChunk(chunk, stream, depth);
     if (res != ResOK)
@@ -678,7 +678,7 @@ void ArenaChunkInsert(Arena arena, Chunk chunk) {
   AVER(updatedTree);
   TreeBalance(&updatedTree);
   arena->chunkTree = updatedTree;
-  RingAppend(&arena->chunkRing, &chunk->arenaRing);
+  RingAppend(ArenaChunkRing(arena), &chunk->arenaRing);
 
   arena->reserved += ChunkReserved(chunk);
 
@@ -707,7 +707,7 @@ void ArenaChunkRemoved(Arena arena, Chunk chunk)
 
   if (chunk == arena->primary) {
     /* The primary chunk must be the last chunk to be removed. */
-    AVER(RingIsSingle(&arena->chunkRing));
+    AVER(RingIsSingle(ArenaChunkRing(arena)));
     AVER(arena->reserved == 0);
     arena->primary = NULL;
   }
@@ -762,7 +762,7 @@ static Res arenaAllocPage(Addr *baseReturn, Arena arena, Pool pool)
   res = arenaAllocPageInChunk(baseReturn, arena->primary, pool);
   if (res != ResOK) {
     Ring node, next;
-    RING_FOR(node, &arena->chunkRing, next) {
+    RING_FOR(node, ArenaChunkRing(arena), next) {
       Chunk chunk = RING_ELT(Chunk, arenaRing, node);
       if (chunk != arena->primary) {
         res = arenaAllocPageInChunk(baseReturn, chunk, pool);
diff --git a/mps/code/gcbench.c b/mps/code/gcbench.c
index 2ae97104930..7aa28eb4561 100644
--- a/mps/code/gcbench.c
+++ b/mps/code/gcbench.c
@@ -248,8 +248,7 @@ static void arena_setup(gcthread_fn_t fn,
   } MPS_ARGS_END(args);
   watch(fn, name);
   mps_arena_park(arena);
-  printf("%u chunks\n", (unsigned)TreeDebugCount(ArenaChunkTree(arena),
-                                                 ChunkCompare, ChunkKey));
+  printf("%u chunks\n", (unsigned)RingLength(ArenaChunkRing(arena)));
   mps_pool_destroy(pool);
   mps_fmt_destroy(format);
   if (ngen > 0)
diff --git a/mps/code/mpm.h b/mps/code/mpm.h
index a5ac16b41a2..6f34cd4e020 100644
--- a/mps/code/mpm.h
+++ b/mps/code/mpm.h
@@ -528,6 +528,7 @@ extern Ring GlobalsRememberedSummaryRing(Globals);
 #define ArenaGreyRing(arena, rank) (&(arena)->greyRing[rank])
 #define ArenaPoolRing(arena) (&ArenaGlobals(arena)->poolRing)
 #define ArenaChunkTree(arena) RVALUE((arena)->chunkTree)
+#define ArenaChunkRing(arena) RVALUE(&(arena)->chunkRing)
 
 extern Bool ArenaGrainSizeCheck(Size size);
 #define AddrArenaGrainUp(addr, arena) AddrAlignUp(addr, ArenaGrainSize(arena))
diff --git a/mps/code/ring.c b/mps/code/ring.c
index 2f4be5066f2..9ceeecfa232 100644
--- a/mps/code/ring.c
+++ b/mps/code/ring.c
@@ -65,14 +65,14 @@ Bool RingIsSingle(Ring ring)
  * See <design/ring/#length>
  */
 
-Size RingLength(Ring ring)
+Count RingLength(Ring ring)
 {
-  Size size = 0;
+  Count length = 0;
   Ring node, next;
   AVERT(Ring, ring);
   RING_FOR(node, ring, next)
-    ++ size;
-  return size;
+    ++ length;
+  return length;
 }
 
 
diff --git a/mps/code/ring.h b/mps/code/ring.h
index 9cb915f4bf4..c7d154dbe5c 100644
--- a/mps/code/ring.h
+++ b/mps/code/ring.h
@@ -30,7 +30,7 @@ typedef struct RingStruct {     /* double-ended queue structure */
 extern Bool RingCheck(Ring ring);
 extern Bool RingCheckSingle(Ring ring);
 extern Bool RingIsSingle(Ring ring);
-extern Size RingLength(Ring ring);
+extern Count RingLength(Ring ring);
 
 /* .ring.init: See <design/ring/#init> */
 extern void (RingInit)(Ring ring);
diff --git a/mps/design/ring.txt b/mps/design/ring.txt
index c0f4d9adfd4..1935cd02b29 100644
--- a/mps/design/ring.txt
+++ b/mps/design/ring.txt
@@ -112,7 +112,7 @@ additionally checks that ``ring`` is a singleton (see
 _`.is.single`: Return ``TRUE`` if ``ring`` is a singleton (see
 `.def.singleton`_).
 
-``Size RingLength(Ring ring)``
+``Count RingLength(Ring ring)``
 
 _`.length`: Return the number of elements in the ring, not counting
 ``ring`` itself. This therefore returns 0 for singleton rings, and for
diff --git a/mps/test/function/232.c b/mps/test/function/232.c
new file mode 100644
index 00000000000..398f1586dd9
--- /dev/null
+++ b/mps/test/function/232.c
@@ -0,0 +1,59 @@
+/* 
+TEST_HEADER
+ id = $Id: //info.ravenbrook.com/project/mps/branch/2015-08-11/compact/test/function/229.c#1 $
+ summary = test arena extension and compaction
+ language = c
+ link = testlib.o
+ parameters = SIZE=1024*1024 ITERATIONS=100
+END_HEADER
+*/
+
+#include "mpm.h"
+#include "mpscmvff.h"
+#include "testlib.h"
+
+static void check_chunks(mps_arena_t arena, unsigned expected)
+{
+  unsigned chunks = (unsigned)RingLength(ArenaChunkRing((Arena)arena));
+  asserts(chunks == expected, "expected %u chunks, got %u", expected, chunks);
+}
+
+static void test(void)
+{
+  mps_arena_t arena;
+  mps_pool_t pool;
+  mps_addr_t block[ITERATIONS];
+  unsigned i;
+
+  MPS_ARGS_BEGIN(args) {
+    MPS_ARGS_ADD(args, MPS_KEY_ARENA_SIZE, SIZE);
+    die(mps_arena_create_k(&arena, mps_arena_class_vm(), args), "arena_create");
+  } MPS_ARGS_END(args);
+
+  MPS_ARGS_BEGIN(args) {
+    MPS_ARGS_ADD(args, MPS_KEY_SPARE, 0);
+    die(mps_pool_create_k(&pool, arena, mps_class_mvff(), args), "pool_create");
+  } MPS_ARGS_END(args);
+  check_chunks(arena, 1);
+
+  for (i = 0; i < ITERATIONS; ++i) {
+    die(mps_alloc(&block[i], pool, SIZE), "mps_alloc");
+    check_chunks(arena, i + 2);
+  }
+
+  for (i = ITERATIONS; i > 0; --i) {
+    mps_free(pool, block[i - 1], SIZE);
+    mps_arena_collect(arena); /* ensure ArenaCompact called via TraceReclaim */
+    check_chunks(arena, i);
+  }
+
+  mps_pool_destroy(pool);
+  mps_arena_destroy(arena);
+}
+
+int main(void)
+{
+  easy_tramp(test);
+  pass();
+  return 0;
+}
diff --git a/mps/test/testsets/passing b/mps/test/testsets/passing
index fde2ca5de8d..b29ffc686cd 100644
--- a/mps/test/testsets/passing
+++ b/mps/test/testsets/passing
@@ -168,4 +168,5 @@ function/224.c
 % 225 -- no such test
 function/226.c
 function/227.c
-function/229.c
\ No newline at end of file
+function/229.c
+function/232.c