diff --git a/io.c b/io.c
index 0c7beedf23..f91f23ae06 100644
--- a/io.c
+++ b/io.c
@@ -6201,7 +6201,7 @@ pipe_open_s(VALUE prog, const char *modestr, int fmode, convconfig_t *convconfig
  *  If a block is given, Ruby will run the command as a child connected
  *  to Ruby with a pipe. Ruby's end of the pipe will be passed as a
  *  parameter to the block.
- *  At the end of block, Ruby close the pipe and sets <code>$?</code>.
+ *  At the end of block, Ruby closes the pipe and sets <code>$?</code>.
  *  In this case <code>IO.popen</code> returns
  *  the value of the block.
  *