diff --git a/bundle.c b/bundle.c
index f82baae3b..08020bc3a 100644
--- a/bundle.c
+++ b/bundle.c
@@ -23,50 +23,102 @@ static void add_to_ref_list(const unsigned char *sha1, const char *name,
 	list->nr++;
 }
 
-/* returns an fd */
-int read_bundle_header(const char *path, struct bundle_header *header)
+/* Eventually this should go to strbuf.[ch] */
+static int strbuf_readline_fd(struct strbuf *sb, int fd)
 {
-	char buffer[1024];
-	int fd;
-	long fpos;
-	FILE *ffd = fopen(path, "rb");
+	strbuf_reset(sb);
+
+	while (1) {
+		char ch;
+		ssize_t len = xread(fd, &ch, 1);
+		if (len < 0)
+			return -1;
+		strbuf_addch(sb, ch);
+		if (ch == '\n')
+			break;
+	}
+	return 0;
+}
 
-	if (!ffd)
-		return error("could not open '%s'", path);
-	if (!fgets(buffer, sizeof(buffer), ffd) ||
-			strcmp(buffer, bundle_signature)) {
-		fclose(ffd);
-		return error("'%s' does not look like a v2 bundle file", path);
+static int parse_bundle_header(int fd, struct bundle_header *header,
+			       const char *report_path)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int status = 0;
+
+	/* The bundle header begins with the signature */
+	if (strbuf_readline_fd(&buf, fd) ||
+	    strcmp(buf.buf, bundle_signature)) {
+		if (report_path)
+			error("'%s' does not look like a v2 bundle file",
+			      report_path);
+		status = -1;
+		goto abort;
 	}
-	while (fgets(buffer, sizeof(buffer), ffd)
-			&& buffer[0] != '\n') {
-		int is_prereq = buffer[0] == '-';
-		int offset = is_prereq ? 1 : 0;
-		int len = strlen(buffer);
+
+	/* The bundle header ends with an empty line */
+	while (!strbuf_readline_fd(&buf, fd) &&
+	       buf.len && buf.buf[0] != '\n') {
 		unsigned char sha1[20];
-		struct ref_list *list = is_prereq ? &header->prerequisites
-			: &header->references;
-		char delim;
-
-		if (len && buffer[len - 1] == '\n')
-			buffer[len - 1] = '\0';
-		if (get_sha1_hex(buffer + offset, sha1)) {
-			warning("unrecognized header: %s", buffer);
-			continue;
+		int is_prereq = 0;
+
+		if (*buf.buf == '-') {
+			is_prereq = 1;
+			strbuf_remove(&buf, 0, 1);
+		}
+		strbuf_rtrim(&buf);
+
+		/*
+		 * Tip lines have object name, SP, and refname.
+		 * Prerequisites have object name that is optionally
+		 * followed by SP and subject line.
+		 */
+		if (get_sha1_hex(buf.buf, sha1) ||
+		    (40 <= buf.len && !isspace(buf.buf[40])) ||
+		    (!is_prereq && buf.len <= 40)) {
+			if (report_path)
+				error("unrecognized header: %s%s (%d)",
+				      (is_prereq ? "-" : ""), buf.buf, (int)buf.len);
+			status = -1;
+			break;
+		} else {
+			if (is_prereq)
+				add_to_ref_list(sha1, "", &header->prerequisites);
+			else
+				add_to_ref_list(sha1, buf.buf + 41, &header->references);
 		}
-		delim = buffer[40 + offset];
-		if (!isspace(delim) && (delim != '\0' || !is_prereq))
-			die ("invalid header: %s", buffer);
-		add_to_ref_list(sha1, isspace(delim) ?
-				buffer + 41 + offset : "", list);
 	}
-	fpos = ftell(ffd);
-	fclose(ffd);
-	fd = open(path, O_RDONLY);
+
+ abort:
+	if (status) {
+		close(fd);
+		fd = -1;
+	}
+	strbuf_release(&buf);
+	return fd;
+}
+
+int read_bundle_header(const char *path, struct bundle_header *header)
+{
+	int fd = open(path, O_RDONLY);
+
 	if (fd < 0)
 		return error("could not open '%s'", path);
-	lseek(fd, fpos, SEEK_SET);
-	return fd;
+	return parse_bundle_header(fd, header, path);
+}
+
+int is_bundle(const char *path, int quiet)
+{
+	struct bundle_header header;
+	int fd = open(path, O_RDONLY);
+
+	if (fd < 0)
+		return 0;
+	memset(&header, 0, sizeof(header));
+	fd = parse_bundle_header(fd, &header, quiet ? NULL : path);
+	if (fd >= 0)
+		close(fd);
+	return (fd >= 0);
 }
 
 static int list_refs(struct ref_list *r, int argc, const char **argv)
diff --git a/bundle.h b/bundle.h
index c5a22c8d1..1584e4d82 100644
--- a/bundle.h
+++ b/bundle.h
@@ -14,6 +14,7 @@ struct bundle_header {
 	struct ref_list references;
 };
 
+int is_bundle(const char *path, int quiet);
 int read_bundle_header(const char *path, struct bundle_header *header);
 int create_bundle(struct bundle_header *header, const char *path,
 		int argc, const char **argv);
diff --git a/transport.c b/transport.c
index 57138d908..4ff21ad28 100644
--- a/transport.c
+++ b/transport.c
@@ -859,28 +859,6 @@ static int is_local(const char *url)
 		has_dos_drive_prefix(url);
 }
 
-static int is_gitfile(const char *url)
-{
-	struct stat st;
-	char buf[9];
-	int fd, len;
-	if (stat(url, &st))
-		return 0;
-	if (!S_ISREG(st.st_mode))
-		return 0;
-	if (st.st_size < 10 || st.st_size > 9 + PATH_MAX)
-		return 0;
-
-	fd = open(url, O_RDONLY);
-	if (fd < 0)
-		die_errno("Error opening '%s'", url);
-	len = read_in_full(fd, buf, sizeof(buf));
-	close(fd);
-	if (len != sizeof(buf))
-		die("Error reading %s", url);
-	return !prefixcmp(buf, "gitdir: ");
-}
-
 static int is_file(const char *url)
 {
 	struct stat buf;
@@ -929,7 +907,7 @@ struct transport *transport_get(struct remote *remote, const char *url)
 		ret->fetch = fetch_objs_via_rsync;
 		ret->push = rsync_transport_push;
 		ret->smart_options = NULL;
-	} else if (is_local(url) && is_file(url) && !is_gitfile(url)) {
+	} else if (is_local(url) && is_file(url) && is_bundle(url, 1)) {
 		struct bundle_transport_data *data = xcalloc(1, sizeof(*data));
 		ret->data = data;
 		ret->get_refs_list = get_refs_from_bundle;