diff --git a/Source/kwsys/SystemTools.cxx b/Source/kwsys/SystemTools.cxx
index 33d3e64c6..61cca36ce 100644
--- a/Source/kwsys/SystemTools.cxx
+++ b/Source/kwsys/SystemTools.cxx
@@ -2293,7 +2293,8 @@ bool SystemTools::FileIsDirectory(const char* name)
   // Remove any trailing slash from the name.
   char buffer[KWSYS_SYSTEMTOOLS_MAXPATH];
   int last = static_cast<int>(strlen(name))-1;
-  if(last >= 0 && (name[last] == '/' || name[last] == '\\'))
+  if(last > 0 && (name[last] == '/' || name[last] == '\\')
+    && strcmp(name, "/") !=0)
     {
     memcpy(buffer, name, last);
     buffer[last] = 0;