diff --git a/Documentation/git-repo.adoc b/Documentation/git-repo.adoc
index 70f0a6d2e4..c4a78277df 100644
--- a/Documentation/git-repo.adoc
+++ b/Documentation/git-repo.adoc
@@ -8,8 +8,8 @@ git-repo - Retrieve information about the repository
 SYNOPSIS
 --------
 [synopsis]
-git repo info [--format=(keyvalue|nul)] [-z] [--all | <key>...]
-git repo structure [--format=(table|keyvalue|nul)]
+git repo info [--format=(keyvalue|nul) | -z] [--all | <key>...]
+git repo structure [--format=(table|keyvalue|nul) | -z]
 
 DESCRIPTION
 -----------
@@ -19,7 +19,7 @@ THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
 
 COMMANDS
 --------
-`info [--format=(keyvalue|nul)] [-z] [--all | <key>...]`::
+`info [--format=(keyvalue|nul) | -z] [--all | <key>...]`::
 	Retrieve metadata-related information about the current repository. Only
 	the requested data will be returned based on their keys (see "INFO KEYS"
 	section below).
@@ -44,13 +44,12 @@ supported:
 +
 `-z` is an alias for `--format=nul`.
 
-`structure [--format=(table|keyvalue|nul)]`::
+`structure [--format=(table|keyvalue|nul) | -z]`::
 	Retrieve statistics about the current repository structure. The
 	following kinds of information are reported:
 +
 * Reference counts categorized by type
 * Reachable object counts categorized by type
-
 +
 The output format can be chosen through the flag `--format`. Three formats are
 supported:
@@ -72,6 +71,8 @@ supported:
 	the delimiter between the key and value instead of '='. Unlike the
 	`keyvalue` format, values containing "unusual" characters are never
 	quoted.
++
+`-z` is an alias for `--format=nul`.
 
 INFO KEYS
 ---------
diff --git a/builtin/repo.c b/builtin/repo.c
index 2a653bd3ea..0dd41b1778 100644
--- a/builtin/repo.c
+++ b/builtin/repo.c
@@ -15,8 +15,8 @@
 #include "utf8.h"
 
 static const char *const repo_usage[] = {
-	"git repo info [--format=(keyvalue|nul)] [-z] [--all | <key>...]",
-	"git repo structure [--format=(table|keyvalue|nul)]",
+	"git repo info [--format=(keyvalue|nul) | -z] [--all | <key>...]",
+	"git repo structure [--format=(table|keyvalue|nul) | -z]",
 	NULL
 };
 
@@ -529,6 +529,10 @@ static int cmd_repo_structure(int argc, const char **argv, const char *prefix,
 		OPT_CALLBACK_F(0, "format", &format, N_("format"),
 			       N_("output format"),
 			       PARSE_OPT_NONEG, parse_format_cb),
+		OPT_CALLBACK_F('z', NULL, &format, NULL,
+			       N_("synonym for --format=nul"),
+			       PARSE_OPT_NONEG | PARSE_OPT_NOARG,
+			       parse_format_cb),
 		OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
 		OPT_END()
 	};
diff --git a/t/t1901-repo-structure.sh b/t/t1901-repo-structure.sh
index 36a71a144e..df7d4ea524 100755
--- a/t/t1901-repo-structure.sh
+++ b/t/t1901-repo-structure.sh
@@ -101,6 +101,13 @@ test_expect_success 'keyvalue and nul format' '
 		tr "\n=" "\0\n" <expect >expect_nul &&
 		git repo structure --format=nul >out 2>err &&
 
+		test_cmp expect_nul out &&
+		test_line_count = 0 err &&
+
+		# "-z", as a synonym to "--format=nul", participates in the
+		# usual "last one wins" rule.
+		git repo structure --format=table -z >out 2>err &&
+
 		test_cmp expect_nul out &&
 		test_line_count = 0 err
 	)