Index: share/man/man9/style.9
===================================================================
--- share/man/man9/style.9
+++ share/man/man9/style.9
@@ -756,9 +756,9 @@
 !(p = f())
 .Ed
 .Pp
-Do not use
-.Ic \&!
-for tests unless it is a boolean, e.g., use:
+Only boolean variables should be tested without a comparison, or with
+.Ic \&! .
+For example, use:
 .Bd -literal
 if (*p == '\e0')
 .Ed
@@ -768,6 +768,16 @@
 if (!*p)
 .Ed
 .Pp
+Use:
+.Bd -literal
+if (count != 0)
+.Ed
+.Pp
+not:
+.Bd -literal
+if (count)
+.Ed
+.Pp
 Routines returning
 .Vt "void *"
 should not have their return values cast