diff --git a/JavaScriptCore/API/JSValueRef.cpp b/JavaScriptCore/API/JSValueRef.cpp
index a12cc34..518fc7b 100644
--- a/JavaScriptCore/API/JSValueRef.cpp
+++ b/JavaScriptCore/API/JSValueRef.cpp
@@ -211,6 +211,12 @@
     ExecState* exec = toJS(ctx);
     APIEntryShim entryShim(exec);
 
+    // Our JSValue representation relies on a standard bit pattern for NaN. NaNs
+    // generated internally to JavaScriptCore naturally have that representation,
+    // but an external NaN might not.
+    if (isnan(value))
+        value = NaN;
+
     return toRef(exec, jsNumber(exec, value));
 }
 
diff --git a/JavaScriptCore/wtf/dtoa.cpp b/JavaScriptCore/wtf/dtoa.cpp
index 6289d04..e63be90 100644
--- a/JavaScriptCore/wtf/dtoa.cpp
+++ b/JavaScriptCore/wtf/dtoa.cpp
@@ -168,6 +168,7 @@
 #endif
 
 #define INFNAN_CHECK
+#define No_Hex_NaN
 
 #if defined(IEEE_8087) + defined(IEEE_MC68k) + defined(IEEE_ARM) != 1
 Exactly one of IEEE_8087, IEEE_ARM or IEEE_MC68k should be defined.