diff --git a/base/env.jl b/base/env.jl
index 78e2e0515145a..6482d7737c56e 100644
--- a/base/env.jl
+++ b/base/env.jl
@@ -91,7 +91,7 @@ if is_windows()
     function next(hash::EnvHash, block::Tuple{Ptr{UInt16},Ptr{UInt16}})
         pos = block[1]
         blk = block[2]
-        len = ccall(:wcslen, UInt, (Ptr{UInt16},), pos) + 1
+        len = ccall(:wcslen, UInt, (Ptr{UInt16},), pos)
         buf = Array{UInt16}(len)
         unsafe_copy!(pointer(buf), pos, len)
         env = transcode(String, buf)
@@ -99,7 +99,7 @@ if is_windows()
         if m === nothing
             error("malformed environment entry: $env")
         end
-        return (Pair{String,String}(m.captures[1], m.captures[2]), (pos+len*2, blk))
+        return (Pair{String,String}(m.captures[1], m.captures[2]), (pos+(len+1)*2, blk))
     end
 else # !windows
     start(::EnvHash) = 0
diff --git a/test/env.jl b/test/env.jl
index 23e8710398cab..030fe3cf9b590 100644
--- a/test/env.jl
+++ b/test/env.jl
@@ -63,3 +63,10 @@ end
 
 # Test for #10853
 @test withenv(Dict{Any,Any}()...) do; true; end
+
+# Test for #18141
+for (k, v) in ENV
+    if length(v) > 0
+        @test v[end] != '\0'
+    end
+end