diff --git a/ProcessWin32.c b/ProcessWin32.c
index f6c2ea8b6105561337d6ed3ed33d0e602e378546..774d5c7217bb7ffc2ae83c88ac816242d1c73e57 100644
--- a/ProcessWin32.c
+++ b/ProcessWin32.c
@@ -460,7 +460,7 @@ void kwsysProcess_SetCommand(kwsysProcess* cp, char const* const* command)
 
       /* Add the length of the argument, plus 3 for the double quotes
          and space separating the arguments.  */
-      length += strlen(*arg) + 3;
+      length += (int)strlen(*arg) + 3;
       
       /* Scan the string to find characters that need escaping.  */
       for(c=*arg; *c; ++c)