1 files changed, 3 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 8a5ba7db3d1..947c2827b8e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7117,6 +7117,9 @@ AC_CACHE_CHECK([for usable FIONREAD], [emacs_cv_usable_FIONREAD],
                             #ifdef USG5_4
                             # include <sys/filio.h>
                             #endif
+                            #ifdef HAVE_UNISTD_H
+                            # include <unistd.h> /* defines ioctl() on Solaris */
+                            #endif
                           ]],
                           [[int foo = ioctl (0, FIONREAD, &foo);]])],
          [emacs_cv_usable_FIONREAD=yes],