diff --git a/mozilla/js/src/xpconnect/src/xpcwrappedjsclass.cpp b/mozilla/js/src/xpconnect/src/xpcwrappedjsclass.cpp
index ee0c764505f..964dd9ee994 100644
--- a/mozilla/js/src/xpconnect/src/xpcwrappedjsclass.cpp
+++ b/mozilla/js/src/xpconnect/src/xpcwrappedjsclass.cpp
@@ -1497,7 +1497,8 @@ pre_call_clean_up:
 
             if(isArray)
             {
-                if(!XPCConvert::JSArray2Native(ccx, (void**)&pv->val, val,
+                if(array_count &&
+                   !XPCConvert::JSArray2Native(ccx, (void**)&pv->val, val,
                                                array_count, array_count,
                                                datum_type,
                                                useAllocator, &param_iid,
diff --git a/mozilla/js/src/xpconnect/src/xpcwrappednative.cpp b/mozilla/js/src/xpconnect/src/xpcwrappednative.cpp
index cb249fa0a2d..fb4a1d225d4 100644
--- a/mozilla/js/src/xpconnect/src/xpcwrappednative.cpp
+++ b/mozilla/js/src/xpconnect/src/xpcwrappednative.cpp
@@ -1979,7 +1979,8 @@ XPCWrappedNative::CallMethod(XPCCallContext& ccx,
 
                 if(isArray)
                 {
-                    if(!XPCConvert::JSArray2Native(ccx, (void**)&dp->val, src,
+                    if(array_count &&
+                       !XPCConvert::JSArray2Native(ccx, (void**)&dp->val, src,
                                                    array_count, array_capacity,
                                                    datum_type,
                                                    useAllocator,