--- a/js/src/vm/UnboxedObject.cpp
+++ b/js/src/vm/UnboxedObject.cpp
@@ -1226,48 +1226,48 @@ UnboxedArrayObject::objectMovedDuringMin
 // Possible capacities for unboxed arrays. Some of these capacities might seem
 // a little weird, but were chosen to allow the inline data of objects of each
 // size to be fully utilized for arrays of the various types on both 32 bit and
 // 64 bit platforms.
 /* static */ const uint32_t
 UnboxedArrayObject::CapacityArray[] = {
     UINT32_MAX, // For CapacityMatchesLengthIndex.
     0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 16, 17, 18, 20, 24, 26, 32, 34, 36, 48, 52, 64, 68,
-    128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288,
+    72, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288,
     1048576, 2097152, 3145728, 4194304, 5242880, 6291456, 7340032, 8388608, 9437184, 11534336,
     13631488, 15728640, 17825792, 20971520, 24117248, 27262976, 31457280, 35651584, 40894464,
     46137344, 52428800, 59768832, MaximumCapacity
 };
 
 static const uint32_t
 Pow2CapacityIndexes[] = {
     1,  // 1
     2,  // 2
     4,  // 4
     8,  // 8
     13, // 16
     19, // 32
     24, // 64
-    26, // 128
-    27, // 256
-    28, // 512
-    29, // 1024
-    30, // 2048
-    31, // 4096
-    32, // 8192
-    33, // 16384
-    34, // 32768
-    35, // 65536
-    36, // 131072
-    37, // 262144
-    38, // 524288
-    39  // 1048576
+    27, // 128
+    28, // 256
+    29, // 512
+    30, // 1024
+    31, // 2048
+    32, // 4096
+    33, // 8192
+    34, // 16384
+    35, // 32768
+    36, // 65536
+    37, // 131072
+    38, // 262144
+    39, // 524288
+    40  // 1048576
 };
 
-static const uint32_t MebiCapacityIndex = 39;
+static const uint32_t MebiCapacityIndex = 40;
 
 /* static */ uint32_t
 UnboxedArrayObject::chooseCapacityIndex(uint32_t capacity, uint32_t length)
 {
     // Note: the structure and behavior of this method follow along with
     // NativeObject::goodAllocated. Changes to the allocation strategy in one
     // should generally be matched by the other.