diff --git a/js/public/HeapAPI.h b/js/public/HeapAPI.h
index e16d9f5f93d..402ae0f2c48 100644
--- a/js/public/HeapAPI.h
+++ b/js/public/HeapAPI.h
@@ -13,10 +13,6 @@
 
 #include "js/Utility.h"
 
-#ifdef MOZ_B2G
-#define JS_GC_CHUNK_SIZE_SMALL
-#endif
-
 /* These values are private to the JS engine. */
 namespace js {
 
@@ -36,11 +32,7 @@ const size_t ArenaShift = 12;
 const size_t ArenaSize = size_t(1) << ArenaShift;
 const size_t ArenaMask = ArenaSize - 1;
 
-#ifdef JS_GC_CHUNK_SIZE_SMALL
-const size_t ChunkShift = 18;
-#else
 const size_t ChunkShift = 20;
-#endif
 const size_t ChunkSize = size_t(1) << ChunkShift;
 const size_t ChunkMask = ChunkSize - 1;
 
@@ -49,13 +41,8 @@ const size_t CellSize = size_t(1) << CellShift;
 const size_t CellMask = CellSize - 1;
 
 /* These are magic constants derived from actual offsets in gc/Heap.h. */
-#ifdef JS_GC_CHUNK_SIZE_SMALL
-const size_t ChunkMarkBitmapOffset = 258104;
-const size_t ChunkMarkBitmapBits = 31744;
-#else
 const size_t ChunkMarkBitmapOffset = 1032352;
 const size_t ChunkMarkBitmapBits = 129024;
-#endif
 const size_t ChunkRuntimeOffset = ChunkSize - sizeof(void*);
 const size_t ChunkLocationOffset = ChunkSize - 2 * sizeof(void*) - sizeof(uint64_t);
 
diff --git a/js/src/gc/Heap.h b/js/src/gc/Heap.h
index 97d8469581b..b6e664f0da6 100644
--- a/js/src/gc/Heap.h
+++ b/js/src/gc/Heap.h
@@ -700,12 +700,7 @@ const size_t BytesPerArenaWithHeader = ArenaSize + ArenaBitmapBytes;
 const size_t ChunkDecommitBitmapBytes = ChunkSize / ArenaSize / JS_BITS_PER_BYTE;
 const size_t ChunkBytesAvailable = ChunkSize - sizeof(ChunkInfo) - ChunkDecommitBitmapBytes;
 const size_t ArenasPerChunk = ChunkBytesAvailable / BytesPerArenaWithHeader;
-
-#ifdef JS_GC_CHUNK_SIZE_SMALL
-static_assert(ArenasPerChunk == 62, "Do not accidentally change our heap's density.");
-#else
 static_assert(ArenasPerChunk == 252, "Do not accidentally change our heap's density.");
-#endif
 
 /* A chunk bitmap contains enough mark bits for all the cells in a chunk. */
 struct ChunkBitmap