diff --git a/doc/command_injection.rdoc b/doc/command_injection.rdoc
index 246b2e6afe..ee33d4a04e 100644
--- a/doc/command_injection.rdoc
+++ b/doc/command_injection.rdoc
@@ -7,11 +7,17 @@ They should not be called with unknown or unsanitized commands.
These methods include:
+- Kernel.exec
+- Kernel.spawn
- Kernel.system
-- Kernel.open
- {\`command` (backtick method)}[rdoc-ref:Kernel#`]
(also called by the expression %x[command]).
-- IO.popen(command).
+- IO.popen (when called with other than "-").
+
+Some methods execute a system command only if the given path name starts
+with a |:
+
+- Kernel.open(command).
- IO.read(command).
- IO.write(command).
- IO.binread(command).
@@ -21,7 +27,7 @@ These methods include:
- URI.open(command).
Note that some of these methods do not execute commands when called
-from subclass \File:
+from subclass +File+:
- File.read(path).
- File.write(path).