diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 9e823582ff..e97b6c69f5 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -373,6 +373,9 @@
     This port does not support interrupts or a real timer (and hence no
     round robin scheduler)  Otherwise, it is complete.
   </li>
+  <p>NOTE: This target will not run on Cygwin probably for many reasons but
+    first off because it uses some of the same symbols as does cygwind.dll.
+  </p>
 
   <li><code>arch/arm</code>:
     This directory holds common ARM architectures.  At present, this includes
diff --git a/configs/README.txt b/configs/README.txt
index 1c1252688c..f07e4aaa5d 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -260,6 +260,9 @@ configs/sim
     This port does not support interrupts or a real timer (and hence no
     round robin scheduler)  Otherwise, it is complete.
 
+    NOTE: This target will not run on Cygwin probably for many reasons but
+    first off because it uses some of the same symbols as does cygwind.dll.
+
 configs/c5471evm
     This is a port to the Spectrum Digital C5471 evaluation board.  The
     C5471 is a dual core processor from TI with an ARM7TDMI general purpose