diff --git a/sbin/md5/md5.1 b/sbin/md5/md5.1
--- a/sbin/md5/md5.1
+++ b/sbin/md5/md5.1
@@ -129,6 +129,7 @@
 .Pq Note that this option is not yet useful if multiple files are specified.
 .It Fl p , -passthrough
 Echo stdin to stdout and append the checksum to stdout.
+In this mode, any files specified on the command line are silently ignored.
 .It Fl q , -quiet
 Quiet mode \(em only the checksum is printed out.
 Overrides the
@@ -146,6 +147,7 @@
 .It Fl s Ar string , Fl -string= Ns Ar string
 Print a checksum of the given
 .Ar string .
+In this mode, any files specified on the command line are silently ignored.
 .It Fl t , Fl -time-trial
 Run a built-in time trial.
 For the
diff --git a/sbin/md5/md5.c b/sbin/md5/md5.c
--- a/sbin/md5/md5.c
+++ b/sbin/md5/md5.c
@@ -606,7 +606,7 @@
 		err(1, "Unable to enter capability mode");
 #endif
 
-	if (*argv) {
+	if (*argv && !pflag && string == NULL) {
 		do {
 			const char *filename = *argv;
 			const char *filemode = "rb";
diff --git a/sbin/md5/tests/md5_test.sh b/sbin/md5/tests/md5_test.sh
--- a/sbin/md5/tests/md5_test.sh
+++ b/sbin/md5/tests/md5_test.sh
@@ -204,6 +204,8 @@
 	for opt in -q -qr -rq ; do
 		atf_check -o inline:\"\$out_${i}_${alg}\n\" ${alg} \${opt} in
 	done
+	atf_check -o inline:\"\$inp_${i}\$out_${i}_${alg}\n\" ${alg} -p <in
+	atf_check -o inline:\"\$out_${i}_${alg}\n\" ${alg} -s \"\$inp_${i}\"
 }
 "
 		eval "