diff --git a/UPGRADE.txt b/UPGRADE.txt
index 81f1a5b59c13014edd03b237a3c5f45064bf52b3..3125c1e17355540a92b01b3b49df4da016e66009 100755
--- a/UPGRADE.txt
+++ b/UPGRADE.txt
@@ -12,6 +12,16 @@ Compiling:
   support; systems using that compiler will need to be upgraded to
   a more recent compiler release.
 
+Dialplan Expressions:
+
+* The dialplan expression parser (which handles $[ ... ] constructs)
+  has gone through a major upgrade, but has one incompatible change:
+  spaces are no longer required around expression operators, including
+  string comparisons. However, you can now use quoting to keep strings
+  together for comparison. For more details, please read the
+  doc/README.variables file, and check over your dialplan for possible
+  problems.
+
 Agents:
 
 * The default for ackcall has been changed to "no" instead of "yes"