diff -ur aterm-1.0.1-orig/src/command.c aterm-1.0.1/src/command.c
--- aterm-1.0.1-orig/src/command.c	2020-04-01 12:50:59.222929696 -0400
+++ aterm-1.0.1/src/command.c	2020-04-01 12:49:47.319579199 -0400
@@ -91,10 +91,13 @@
 
 #if defined (__svr4__) || defined (__lnx21__)
 # include <sys/resource.h>	/* for struct rlimit */
-# include <sys/stropts.h>	/* for I_PUSH */
 # define _NEW_TTY_CTRL		/* to get proper defines in <termios.h> */
 #endif
 
+#if defined (__svr4__)
+# include <sys/stropts.h>	/* for I_PUSH */
+#endif
+
 /*}}} */
 
 static unsigned int ModMetaMask, ModNumLockMask;
@@ -672,7 +675,7 @@
 	print_error("can't open slave tty %s", ttydev);
 	exit(EXIT_FAILURE);
     }
-#if defined (__svr4__) || defined (__lnx21__)
+#if defined (__svr4__)
 /*
  * Push STREAMS modules:
  *    ptem: pseudo-terminal hardware emulation module.
@@ -682,6 +685,8 @@
     ioctl(fd, I_PUSH, "ptem");
     ioctl(fd, I_PUSH, "ldterm");
     ioctl(fd, I_PUSH, "ttcompat");
+#elif defined (__lnx21__)
+    /* do nothing */
 #else				/* __svr4__ */
     {
     	/* change ownership of tty to real uid and real group */