diff --git a/usr.bin/ee/ee.c b/usr.bin/ee/ee.c
index 65ca72de49e4..0284b7f662de 100644
--- a/usr.bin/ee/ee.c
+++ b/usr.bin/ee/ee.c
@@ -544,10 +544,11 @@ main(argc, argv)		/* beginning of main program		*/
 int argc;
 char *argv[];
 {
-	int counter;
-
-	for (counter = 1; counter < 24; counter++)
-		signal(counter, SIG_IGN);
+	/* Always read from (and write to) a terminal. */
+	if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO)) {
+		fprintf(stderr, "ee's standard input and output must be a terminal\n");
+		exit(1);
+	}
 
 	signal(SIGCHLD, SIG_DFL);
 	signal(SIGSEGV, SIG_DFL);