diff --git a/lib/pure/osproc.nim b/lib/pure/osproc.nim
index 973ddd47e..aa4eb187b 100644
--- a/lib/pure/osproc.nim
+++ b/lib/pure/osproc.nim
@@ -617,7 +617,7 @@ when defined(Windows) and not defined(useNimRtl):
     when useWinUnicode:
       var tmp = newWideCString(cmdl)
       var ee =
-        if e.str.isNil: newWideCString(nil)
+        if e.str.isNil: newWideCString(cstring(nil))
         else: newWideCString(e.str, e.len)
       var wwd = newWideCString(wd)
       var flags = NORMAL_PRIORITY_CLASS or CREATE_UNICODE_ENVIRONMENT