diff --git a/walk/walk.c b/walk/walk.c
index 3abfbe9..af3f3e1 100644
--- a/walk/walk.c
+++ b/walk/walk.c
@@ -12,34 +12,23 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <errno.h>
+#include <errno.h> /* errno */
 #include <stdbool.h>
-#include <stdio.h>
+#include <stdio.h> /* fprintf(3), stderr, stdout */
 #include <stdlib.h>
-#include <string.h>
+#include <string.h> /* strerror(3) */
+#include <sysexits.h> /* EX_USAGE */
 
 #include <dirent.h>
 #include <getopt.h>
 
-static const char SHORT_USAGE[] = "Usage: walk [OPTION...] [DIRECTORY...]\n";
+static char *dot = "."; /* current directory */
 
-static const char HELP[] =
-	"Recursively walk the specified directories (or current directory, if none is\n"
-	"specified.\n\n"
-	"      -0, --null              separate filenames by a null character\n"
-	"      --help                  display this help and exit\n";
+static char *nul_terminator = "\0";
+static char *newl_terminator = "\n";
+static char *asv_terminator = "\037"; /* ASCII UNIT_SEPARATOR */
 
-static const char ASK_FOR_HELP[] = "Try 'walk --help' for more information.\n";
-
-static const char *const JUST_CURRENT_DIRECTORY[] = {".", NULL};
-
-// Like readdir(3), but resets errno(3) before the call to make it easy to
-// check.
-static struct dirent *readdir2(DIR *const dirp)
-{
-	errno = 0;
-	return readdir(dirp);
-}
+static char *argv0;
 
 // Like realloc(3), but exits the binary in an out-of-memory situation.
 static void *xrealloc(void *ptr, const size_t size)
@@ -69,19 +58,22 @@ static void put_filename(const char *filename, bool null_terminate)
 // Walks the directory named dirname, printing the names of all files it
 // contains (but not the name of the directory itself). Returns 2 if dirname is
 // not a directory and 1 if another error occurs.
-static int walk(const char dirname[], bool null_terminate)
-{
-	DIR *const dir = opendir(dirname);
-	if (!dir) {
-		if (errno != ENOTDIR) {
-			perror(dirname);
-			return 1;
-		}
-		return 2;
+static int
+walk(char *dirname, bool null_terminate){
+	DIR dir;
+	struct dirent *f;
+	char *filename;
+	int retval;
+
+	if((dir = opendir(dirname)) == NULL){
+		fprintf(stdout, "%s: %s: %s\n",
+			argv0, dirname, strerror(errno));
+		return 1 + (errno == ENOTDIR);
 	}
-	int r = 0;
-	char *filename = NULL;
-	for (const struct dirent *f = readdir2(dir); f; f = readdir2(dir)) {
+
+	errno = 0;
+	retval = 0;
+	while((f = readdir(dir)) != NULL){
 		if (strcmp(f->d_name, ".") == 0 || strcmp(f->d_name, "..") == 0)
 			continue;
 		filename = xrealloc(
@@ -93,55 +85,54 @@ static int walk(const char dirname[], bool null_terminate)
 		// Don't worry about it if it's not one (walk(filename) == 2).
 		if ((f->d_type == DT_DIR || f->d_type == DT_UNKNOWN)
 			&& walk(filename, null_terminate) == 1)
-			r = 1;
+			retval = 1;
 	}
 	if (errno) {  // from readdir
 		perror(dirname);
-		r = 1;
+		retval = 1;
 	}
 	free(filename);
 	if (closedir(dir)) {
 		perror(dirname);
-		r = 1;
+		retval = 1;
 	}
-	return r;
+	return retval;
 }
 
-int main(const int argc, char *const argv[])
-{
-	static const struct option long_options[] = {
-		{"help", no_argument, NULL, 'h'},
-		{"null", no_argument, NULL, '0'},
-		{NULL, 0, NULL, 0},
-	};
-	bool null_terminate = false;
-	while (true) {
-		const int c = getopt_long(argc, argv, "0", long_options, NULL);
-		if (c == -1) break;
-		switch (c) {
-		case 'h':
-			fputs(SHORT_USAGE, stdout);
-			fputs(HELP, stdout);
-			return 0;
-		case '0':
-			null_terminate = true;
-			break;
-		case '?':
-			fputs(ASK_FOR_HELP, stderr);
-			return 1;
-		default:
-			fputs("Internal error; please report.\n", stderr);
-			return 1;
+int usage(char *argv0){
+	fprintf(stderr, "Usage: %s (-0n) (-d [delimiter]) (-l [max levels])"
+		" (directories...)\n", argv0);
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+	int c;
+	char *terminator;
+	int retval;
+
+	argv0 = argv[0];
+	if(argc > 0){
+		while((c = getopt(argc, argv, "0d:l:n")) != -1)
+			switch(c){
+			case '0': terminator = nul_terminator; break;
+			case 'd': terminator = optarg; break;
+			case 'l': /* TODO */ break;
+			case 'n': terminator = newl_terminator; break;
+			default: return usage(argv[0]);
+			}
+		argv += optind;
+	}
+
+	retval = 0;
+
+	if(*argv == NULL){
+		put_filename(dot, terminator == nul_terminator);
+		retval |= walk(dot, terminator == nul_terminator);
+	}else
+		for(argv += optind; *argv != NULL; ++argv){
+			put_filename(*argv, terminator == nul_terminator);
+			retval |= walk(*argv, terminator == nul_terminator);
 		}
-	}
 
-	int r = 0;
-	const char *const *const dirs = argc == optind
-		? JUST_CURRENT_DIRECTORY
-		: (const char *const *)argv + optind;
-	for (int i = 0; dirs[i]; ++i) {
-		put_filename(dirs[i], null_terminate);
-		r |= walk(dirs[i], null_terminate);
-	}
-	return r;
+	return retval;
 }