diff --git a/coreutils/sort.c b/coreutils/sort.c
index 1d6c59970..d8df4c532 100644
--- a/coreutils/sort.c
+++ b/coreutils/sort.c
@@ -32,7 +32,7 @@ enum {
 	FLAG_u  = 8,            /* Unique */
 	FLAG_c  = 0x10,         /* Check: no output, exit(!ordered) */
 	FLAG_s  = 0x20,         /* Stable sort, no ascii fallback at end */
-	FLAG_z  = 0x40,         /* Input is null terminated, not \n */
+	FLAG_z  = 0x40,         /* Input and output is NUL terminated, not \n */
 /* These can be applied to search keys, the previous four can't */
 	FLAG_b  = 0x80,         /* Ignore leading blanks */
 	FLAG_r  = 0x100,        /* Reverse */
@@ -396,8 +396,9 @@ int sort_main(int argc, char **argv)
 		if (linecount) linecount = flag+1;
 	}
 	/* Print it */
+	flag = (option_mask32 & FLAG_z) ? '\0' : '\n';
 	for (i = 0; i < linecount; i++)
-		fprintf(outfile, "%s\n", lines[i]);
+		fprintf(outfile, "%s%c", lines[i], flag);
 
 	fflush_stdout_and_exit(EXIT_SUCCESS);
 }
diff --git a/testsuite/README b/testsuite/README
index a44846dbb..b4719e64c 100644
--- a/testsuite/README
+++ b/testsuite/README
@@ -1,6 +1,3 @@
-Update: doesn't work as described. Try "make check" from parent dir...
-* * *
-
 To run the test suite, change to this directory and run "./runtest".  It will
 run all of the test cases, and list those with unexpected outcomes.  Adding the
 -v option will cause it to show expected outcomes as well.  To only run the test
diff --git a/testsuite/runtest b/testsuite/runtest
index 93d5ed6e1..fc8392ac5 100755
--- a/testsuite/runtest
+++ b/testsuite/runtest
@@ -1,5 +1,8 @@
 #!/bin/sh
 
+# Usage:
+# runtest [applet1] [applet2...]
+
 # Run one old-style test.
 # Tests are stored in applet/testcase shell scripts.
 # They are run using "sh -x -e applet/testcase".
diff --git a/testsuite/sort.tests b/testsuite/sort.tests
index 1db7870d4..f700dc0c1 100755
--- a/testsuite/sort.tests
+++ b/testsuite/sort.tests
@@ -107,6 +107,12 @@ a c
 b c
 " ""
 
+testing "sort -z outputs NUL terminated lines" "sort -z input" "\
+one\0three\0two\0\
+" "\
+one\0two\0three\0\
+" ""
+
 testing "sort key doesn't strip leading blanks, disables fallback global sort" \
 "sort -n -k2 -t ' '" " a \n 1 \n 2 \n" "" " 2 \n 1 \n a \n"