diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index 655116b62..caf3bdda1 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,5 +1,7 @@
 2009-08-18  Eric Blake  <ebb9@byu.net>
 
+	* libc/posix/popen.c (popen): Fix documented prototype.
+
 	Improve popen compatibility with glibc.
 	* libc/posix/popen.c (popen): The 2006-08-22 change to use
 	FD_CLOEXEC disagrees with other implementations; instead, use
diff --git a/newlib/libc/posix/popen.c b/newlib/libc/posix/popen.c
index accf76c98..38978c7aa 100644
--- a/newlib/libc/posix/popen.c
+++ b/newlib/libc/posix/popen.c
@@ -43,7 +43,7 @@ INDEX
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
-	FILE *popen(char *<[s]>, char *<[mode]>);
+	FILE *popen(const char *<[s]>, const char *<[mode]>);
 
 	int pclose(FILE *<[f]>);