diff --git a/man3/fopencookie.3 b/man3/fopencookie.3
index 35b01493f..07736e3b2 100644
--- a/man3/fopencookie.3
+++ b/man3/fopencookie.3
@@ -31,7 +31,7 @@ fopencookie \- opening a custom stream
 .BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
 .B #include <stdio.h>
 .PP
-.BI "FILE *fopencookie(void *" cookie ", const char *" mode ,
+.BI "FILE *fopencookie(void *restrict " cookie ", const char *restrict " mode ,
 .BI "                  cookie_io_functions_t " io_funcs );
 .fi
 .SH DESCRIPTION