diff --git a/js/src/jsapi-tests/Makefile.in b/js/src/jsapi-tests/Makefile.in
index ebf14d5f65ac..52f3ca35574d 100644
--- a/js/src/jsapi-tests/Makefile.in
+++ b/js/src/jsapi-tests/Makefile.in
@@ -64,6 +64,7 @@ CPPSRCS = \
   testFunctionProperties.cpp \
   testGCChunkAlloc.cpp \
   testGetPropertyDefault.cpp \
+  testIndexToString.cpp \
   testIntString.cpp \
   testIntern.cpp \
   testLookup.cpp \
diff --git a/js/src/jsapi-tests/testIndexToString.cpp b/js/src/jsapi-tests/testIndexToString.cpp
new file mode 100644
index 000000000000..2fb4dac78a89
--- /dev/null
+++ b/js/src/jsapi-tests/testIndexToString.cpp
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sw=4 et tw=99:
+ */
+
+#include "tests.h"
+
+#include "jsnum.h"
+
+#include "vm/String.h"
+
+BEGIN_TEST(testIndexToString)
+{
+    struct TestPair {
+        uint32 num;
+        const char *expected;
+    } tests[] = {
+        { 0, "0" },
+        { 1, "1" },
+        { 2, "2" },
+        { 9, "9" },
+        { 10, "10" },
+        { 15, "15" },
+        { 16, "16" },
+        { 17, "17" },
+        { 99, "99" },
+        { 100, "100" },
+        { 255, "255" },
+        { 256, "256" },
+        { 257, "257" },
+        { 999, "999" },
+        { 1000, "1000" },
+        { 4095, "4095" },
+        { 4096, "4096" },
+        { 9999, "9999" },
+        { 1073741823, "1073741823" },
+        { 1073741824, "1073741824" },
+        { 1073741825, "1073741825" },
+        { 2147483647, "2147483647" },
+        { 2147483648, "2147483648" },
+        { 2147483649, "2147483649" },
+        { 4294967294, "4294967294" },
+        { 4294967295, "4294967295" },
+    };
+
+    for (size_t i = 0, sz = JS_ARRAY_LENGTH(tests); i < sz; i++) {
+        JSString *str = js::IndexToString(cx, tests[i].num);
+        CHECK(str);
+
+        JSBool match = JS_FALSE;
+        CHECK(JS_StringEqualsAscii(cx, str, tests[i].expected, &match));
+        CHECK(match);
+    }
+
+    return true;
+}
+END_TEST(testIndexToString)
diff --git a/js/src/jsnum.cpp b/js/src/jsnum.cpp
index 185ee13db445..ea341a37399b 100644
--- a/js/src/jsnum.cpp
+++ b/js/src/jsnum.cpp
@@ -51,6 +51,9 @@
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
+
+#include "mozilla/RangedPtr.h"
+
 #include "jstypes.h"
 #include "jsstdint.h"
 #include "jsutil.h"
@@ -80,6 +83,7 @@
 #include "vm/String-inl.h"
 
 using namespace js;
+using namespace mozilla;
 
 #ifndef JS_HAVE_STDINT_H /* Native support is innocent until proven guilty. */
 
@@ -1264,6 +1268,41 @@ NumberToString(JSContext *cx, jsdouble d)
     return NULL;
 }
 
+JSFixedString *
+IndexToString(JSContext *cx, uint32 u)
+{
+    if (JSAtom::hasUintStatic(u))
+        return &JSAtom::uintStatic(u);
+
+    JSCompartment *c = cx->compartment;
+    if (JSFixedString *str = c->dtoaCache.lookup(10, u))
+        return str;
+
+    JSShortString *str = js_NewGCShortString(cx);
+    if (!str)
+        return NULL;
+
+    /* +1, since MAX_LENGTH does not count the null char. */
+    JS_STATIC_ASSERT(JSShortString::MAX_LENGTH + 1 >= sizeof("4294967295"));
+
+    jschar *storage = str->inlineStorageBeforeInit();
+    size_t length = JSShortString::MAX_SHORT_LENGTH;
+    const RangedPtr<jschar> end(storage + length, storage, length + 1);
+    RangedPtr<jschar> cp = end;
+    *cp = '\0';
+
+    do {
+        jsuint newu = u / 10, digit = u % 10;
+        *--cp = '0' + digit;
+        u = newu;
+    } while (u > 0);
+
+    str->initAtOffsetInBuffer(cp.get(), end - cp);
+
+    c->dtoaCache.cache(10, u, str);
+    return str;
+}
+
 bool JS_FASTCALL
 NumberValueToStringBuffer(JSContext *cx, const Value &v, StringBuffer &sb)
 {
diff --git a/js/src/jsnum.h b/js/src/jsnum.h
index 59d25d6bb300..792968bf0a0e 100644
--- a/js/src/jsnum.h
+++ b/js/src/jsnum.h
@@ -208,6 +208,9 @@ NumberValueToStringBuffer(JSContext *cx, const Value &v, StringBuffer &sb);
 extern JSFixedString *
 NumberToString(JSContext *cx, jsdouble d);
 
+extern JSFixedString *
+IndexToString(JSContext *cx, uint32 index);
+
 /*
  * Usually a small amount of static storage is enough, but sometimes we need
  * to dynamically allocate much more.  This struct encapsulates that.
diff --git a/js/src/vm/String-inl.h b/js/src/vm/String-inl.h
index 749d188d954a..434b92b2a3b3 100644
--- a/js/src/vm/String-inl.h
+++ b/js/src/vm/String-inl.h
@@ -197,6 +197,19 @@ JSAtom::unitStatic(jschar c)
     return (JSStaticAtom &)unitStaticTable[c];
 }
 
+inline bool
+JSAtom::hasUintStatic(uint32 u)
+{
+    return u < INT_STATIC_LIMIT;
+}
+
+inline JSStaticAtom &
+JSAtom::uintStatic(uint32 u)
+{
+    JS_ASSERT(hasUintStatic(u));
+    return *reinterpret_cast<JSStaticAtom *>(const_cast<JSString::Data *>(intStaticTable[u]));
+}
+
 inline bool
 JSAtom::hasIntStatic(int32 i)
 {
@@ -207,7 +220,7 @@ inline JSStaticAtom &
 JSAtom::intStatic(jsint i)
 {
     JS_ASSERT(hasIntStatic(i));
-    return (JSStaticAtom &)*intStaticTable[i];
+    return uintStatic(uint32(i));
 }
 
 inline JSLinearString *
diff --git a/js/src/vm/String.h b/js/src/vm/String.h
index 53fd82f8a645..c47f89e38c38 100644
--- a/js/src/vm/String.h
+++ b/js/src/vm/String.h
@@ -660,6 +660,9 @@ class JSAtom : public JSFixedString
      */
     static inline bool isStatic(const void *ptr);
 
+    static inline bool hasUintStatic(uint32 u);
+    static inline JSStaticAtom &uintStatic(uint32 u);
+
     static inline bool hasIntStatic(int32 i);
     static inline JSStaticAtom &intStatic(jsint i);