diff --git a/doc/developer.texi b/doc/developer.texi
index dbe1f5421f..98540c8f99 100644
--- a/doc/developer.texi
+++ b/doc/developer.texi
@@ -131,6 +131,11 @@ designated struct initializers (@samp{struct s x = @{ .i = 17 @};});
 
 @item
 compound literals (@samp{x = (struct s) @{ 17, 23 @};}).
+
+@item
+Implementation defined behavior for signed integers is assumed to match the
+expected behavior for two's complement. Non representable values in integer
+casts are binary truncated. Shift right of signed values uses sign extension.
 @end itemize
 
 These features are supported by all compilers we care about, so we will not