diff --git a/usr.bin/cmp/cmp.c b/usr.bin/cmp/cmp.c
--- a/usr.bin/cmp/cmp.c
+++ b/usr.bin/cmp/cmp.c
@@ -38,6 +38,7 @@
 #include <fcntl.h>
 #include <getopt.h>
 #include <nl_types.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -66,7 +67,6 @@
 static void
 siginfo(int signo)
 {
-
 	info = signo;
 }
 #endif
@@ -244,7 +244,7 @@
 	else {
 		if (zflag && sb1.st_size != sb2.st_size) {
 			if (!sflag)
-				(void) printf("%s %s differ: size\n",
+				(void)printf("%s %s differ: size\n",
 				    file1, file2);
 			exit(DIFF_EXIT);
 		}
diff --git a/usr.bin/cmp/link.c b/usr.bin/cmp/link.c
--- a/usr.bin/cmp/link.c
+++ b/usr.bin/cmp/link.c
@@ -27,6 +27,7 @@
  */
 
 #include <sys/types.h>
+
 #include <err.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -42,7 +43,8 @@
 {
 	char buf1[PATH_MAX], *p1;
 	char buf2[PATH_MAX], *p2;
-	int dfound, len1, len2;
+	ssize_t len1, len2;
+	int dfound;
 	off_t byte;
 	u_char ch;
 
diff --git a/usr.bin/cmp/regular.c b/usr.bin/cmp/regular.c
--- a/usr.bin/cmp/regular.c
+++ b/usr.bin/cmp/regular.c
@@ -37,6 +37,7 @@
 #include <err.h>
 #include <limits.h>
 #include <signal.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
diff --git a/usr.bin/cmp/special.c b/usr.bin/cmp/special.c
--- a/usr.bin/cmp/special.c
+++ b/usr.bin/cmp/special.c
@@ -33,6 +33,7 @@
 
 #include <capsicum_helpers.h>
 #include <err.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 
diff --git a/usr.bin/cmp/tests/cmp_test2.sh b/usr.bin/cmp/tests/cmp_test2.sh
--- a/usr.bin/cmp/tests/cmp_test2.sh
+++ b/usr.bin/cmp/tests/cmp_test2.sh
@@ -31,12 +31,12 @@
 special_body() {
 	echo 0123456789abcdef > a
 	echo 0123456789abcdeg > b
-	atf_check -s exit:0 -o empty -e empty -x "cat a | cmp a -"
-	atf_check -s exit:0 -o empty -e empty -x "cat a | cmp - a"
-	atf_check -s exit:1 -o not-empty -e empty -x "cat b | cmp a -"
-	atf_check -s exit:1 -o not-empty -e empty -x "cat b | cmp - a"
+	atf_check -s exit:0 -o empty -e empty cmp a - <a
+	atf_check -s exit:0 -o empty -e empty cmp - a <a
+	atf_check -s exit:1 -o not-empty -e empty cmp a - <b
+	atf_check -s exit:1 -o not-empty -e empty cmp - a <b
 
-	atf_check -s exit:0 -o empty -e empty -x "cmp a a <&-"
+	atf_check -s exit:0 -o empty -e empty cmp a a <&-
 }
 
 atf_test_case symlink
@@ -112,9 +112,9 @@
 
 	# Test special, too.  The implementation for link is effectively
 	# identical.
-	atf_check -s exit:0 -e empty -x "cat a | cmp -sn 4 b -"
-	atf_check -s exit:0 -e empty -x "cat a | cmp -sn 3 b -"
-	atf_check -s exit:1 -o ignore -x "cat a | cmp -sn 5 b -"
+	atf_check -s exit:0 -e empty cmp -sn 4 b - <a
+	atf_check -s exit:0 -e empty cmp -sn 3 b - <a
+	atf_check -s exit:1 -o ignore cmp -sn 5 b - <a
 }
 
 atf_test_case bflag