From 2a86ef11d74fcd744ab576179030ed4e223da1e1 Mon Sep 17 00:00:00 2001
From: Tony Kelman <tony@kelman.net>
Date: Fri, 8 May 2015 21:13:58 -0700
Subject: [PATCH] Fix #11170, accessing empty env var on Windows

---
 base/env.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/env.jl b/base/env.jl
index ecd213adf718d..c82cd267ecbce 100644
--- a/base/env.jl
+++ b/base/env.jl
@@ -31,7 +31,7 @@ _hasenv(s::AbstractString) = _getenvlen(s)!=0 || GetLastError()!=ERROR_ENVVAR_NO
 function _jl_win_getenv(s::UTF16String,len::UInt32)
     val=zeros(UInt16,len)
     ret=ccall(:GetEnvironmentVariableW,stdcall,UInt32,(Cwstring,Ptr{UInt16},UInt32),s,val,len)
-    if ret==0 || ret != len-1 || val[end] != 0
+    if (ret == 0 && len != 1) || ret != len-1 || val[end] != 0
         error(string("getenv: ", s, ' ', len, "-1 != ", ret, ": ", FormatMessage()))
     end
     val