| Index: src/x64/stub-cache-x64.cc | 
| diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc | 
| index f7b2fe5b40e23c2065cbe2c0aa79c1ee0f7f4527..617f2b848a52a06f8d17c0a019758f6df09963f6 100644 | 
| --- a/src/x64/stub-cache-x64.cc | 
| +++ b/src/x64/stub-cache-x64.cc | 
| @@ -489,7 +489,7 @@ void StoreStubCompiler::GenerateStoreTransition(MacroAssembler* masm, | 
| } | 
| } else if (representation.IsDouble()) { | 
| Label do_store, heap_number; | 
| -    __ AllocateHeapNumber(storage_reg, scratch1, slow); | 
| +    __ AllocateHeapNumber(storage_reg, scratch1, slow, MUTABLE); | 
|  | 
| __ JumpIfNotSmi(value_reg, &heap_number); | 
| __ SmiToInteger32(scratch1, value_reg); | 
|  |