diff --git a/Modules/termios.c b/Modules/termios.c
index a0613837ef9795..c779a757e4fa9b 100644
--- a/Modules/termios.c
+++ b/Modules/termios.c
@@ -27,6 +27,9 @@
 
 #include <termios.h>
 #include <sys/ioctl.h>
+#if defined(__sun) && defined(__SVR4)
+#  include <unistd.h>             // ioctl()
+#endif
 
 /* HP-UX requires that this be included to pick up MDCD, MCTS, MDSR,
  * MDTR, MRI, and MRTS (apparently used internally by some things