diff --git a/share/man/man9/style.9 b/share/man/man9/style.9
--- a/share/man/man9/style.9
+++ b/share/man/man9/style.9
@@ -746,9 +746,10 @@
 !(p = f())
 .Ed
 .Pp
-Do not use
+Do not test without a comparison, or with unary
 .Ic \&!
-for tests unless it is a boolean, e.g., use:
+(except for booleans).
+For example, use:
 .Bd -literal
 if (*p == '\e0')
 .Ed
@@ -758,6 +759,16 @@
 if (!*p)
 .Ed
 .Pp
+Prefer:
+.Bd -literal
+if (count != 0)
+.Ed
+.Pp
+over:
+.Bd -literal
+if (count)
+.Ed
+.Pp
 Routines returning
 .Vt "void *"
 should not have their return values cast