diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index 32e69f7..96eaeee 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -188,6 +188,10 @@
    hopefully nobody starts using "local" before they are reimplemented
    in C ;-)
 
+ - Some versions of shell do not understand "export variable=value",
+   so we write "variable=value" and then "export variable" on two
+   separate lines.
+
  - Use octal escape sequences (e.g. "\302\242"), not hexadecimal (e.g.
    "\xc2\xa2") in printf format strings, since hexadecimal escape
    sequences are not portable.