diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 2db44c3067..005c13729b 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -100,7 +100,7 @@ private:
 DEFINE_bool(harmony_proxies, false, "enable harmony proxies")
 
 // Flags for experimental implementation features.
-DEFINE_bool(unbox_double_arrays, false, "automatically unbox arrays of doubles")
+DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 
 // Flags for Crankshaft.
 #ifdef V8_TARGET_ARCH_MIPS