diff --git a/glue.rs b/glue.rs
index e5a9258e2..65f9b3a03 100644
--- a/glue.rs
+++ b/glue.rs
@@ -95,7 +95,7 @@ pub fn DefineFunctionWithReserved(cx: *mut JSContext, obj: *mut JSObject,
                                   name: *libc::c_char, call: JSNative, nargs: libc::c_uint,
                                   attrs: libc::c_uint) -> *mut JSObject;
 pub fn GetObjectJSClass(obj: *mut JSObject) -> *JSClass;
-pub fn RUST_js_GetErrorMessage(userRef: *libc::c_void, locale: *libc::c_char,
+pub fn RUST_js_GetErrorMessage(userRef: *mut libc::c_void, locale: *libc::c_char,
                                errorNumber: libc::c_uint) -> *JSErrorFormatString;
 pub fn js_IsObjectProxyClass(obj: *mut JSObject) -> bool;
 pub fn js_IsFunctionProxyClass(obj: *mut JSObject) -> bool;
diff --git a/jsglue.cpp b/jsglue.cpp
index c55bfb4d6..2b7a2b9f9 100644
--- a/jsglue.cpp
+++ b/jsglue.cpp
@@ -634,7 +634,7 @@ GetObjectJSClass(JSObject* obj)
 }
 
 const JSErrorFormatString*
-RUST_js_GetErrorMessage(void* userRef, char* locale, uint32_t errorNumber)
+RUST_js_GetErrorMessage(void* userRef, const char* locale, uint32_t errorNumber)
 {
     return js_GetErrorMessage(userRef, locale, errorNumber);
 }