diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt
index b8fafb1e8b..a5e8b36f62 100644
--- a/Documentation/git-interpret-trailers.txt
+++ b/Documentation/git-interpret-trailers.txt
@@ -56,8 +56,9 @@ least one Git-generated or user-configured trailer and consists of at
 least 25% trailers.
 The group must be preceded by one or more empty (or whitespace-only) lines.
 The group must either be at the end of the message or be the last
-non-whitespace lines before a line that starts with '---'. Such three
-minus signs start the patch part of the message.
+non-whitespace lines before a line that starts with '---' (followed by a
+space or the end of the line). Such three minus signs start the patch
+part of the message. See also `--no-divider` below.
 
 When reading trailers, there can be whitespaces after the
 token, the separator and the value. There can also be whitespaces
@@ -125,6 +126,11 @@ OPTIONS
 	A convenience alias for `--only-trailers --only-input
 	--unfold`.
 
+--no-divider::
+	Do not treat `---` as the end of the commit message. Use this
+	when you know your input contains just the commit message itself
+	(and not an email or the output of `git format-patch`).
+
 CONFIGURATION VARIABLES
 -----------------------
 
diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
index b742539d4d..4b87e0dd2e 100644
--- a/builtin/interpret-trailers.c
+++ b/builtin/interpret-trailers.c
@@ -104,6 +104,7 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "unfold", &opts.unfold, N_("join whitespace-continued values")),
 		{ OPTION_CALLBACK, 0, "parse", &opts, NULL, N_("set parsing options"),
 			PARSE_OPT_NOARG | PARSE_OPT_NONEG, parse_opt_parse },
+		OPT_BOOL(0, "no-divider", &opts.no_divider, N_("do not treat --- specially")),
 		OPT_CALLBACK(0, "trailer", &trailers, N_("trailer"),
 				N_("trailer(s) to add"), option_parse_trailer),
 		OPT_END()
diff --git a/commit.c b/commit.c
index 5781f9bc67..d6f7f5e4d2 100644
--- a/commit.c
+++ b/commit.c
@@ -1426,10 +1426,10 @@ const char *find_commit_header(const char *msg, const char *key, size_t *out_len
  * Returns the number of bytes from the tail to ignore, to be fed as
  * the second parameter to append_signoff().
  */
-int ignore_non_trailer(const char *buf, size_t len)
+size_t ignore_non_trailer(const char *buf, size_t len)
 {
-	int boc = 0;
-	int bol = 0;
+	size_t boc = 0;
+	size_t bol = 0;
 	int in_old_conflicts_block = 0;
 	size_t cutoff = wt_status_locate_end(buf, len);
 
diff --git a/commit.h b/commit.h
index e2c99d9b04..2b1a734388 100644
--- a/commit.h
+++ b/commit.h
@@ -293,7 +293,7 @@ extern const char *find_commit_header(const char *msg, const char *key,
 				      size_t *out_len);
 
 /* Find the end of the log message, the right place for a new trailer. */
-extern int ignore_non_trailer(const char *buf, size_t len);
+extern size_t ignore_non_trailer(const char *buf, size_t len);
 
 typedef int (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
 				 void *cb_data);
diff --git a/pretty.c b/pretty.c
index 98cf5228f9..8ca29e9281 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1304,6 +1304,9 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 
 	if (skip_prefix(placeholder, "(trailers", &arg)) {
 		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
+
+		opts.no_divider = 1;
+
 		if (*arg == ':') {
 			arg++;
 			for (;;) {
diff --git a/ref-filter.c b/ref-filter.c
index 9bacd32f0a..e1bcb4ca8a 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -264,6 +264,8 @@ static int trailers_atom_parser(const struct ref_format *format, struct used_ato
 	struct string_list params = STRING_LIST_INIT_DUP;
 	int i;
 
+	atom->u.contents.trailer_opts.no_divider = 1;
+
 	if (arg) {
 		string_list_split(&params, arg, ',', -1);
 		for (i = 0; i < params.nr; i++) {
diff --git a/sequencer.c b/sequencer.c
index bd159991e9..9ba873b875 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -226,13 +226,16 @@ static const char *get_todo_path(const struct replay_opts *opts)
  * Returns 3 when sob exists within conforming footer as last entry
  */
 static int has_conforming_footer(struct strbuf *sb, struct strbuf *sob,
-	int ignore_footer)
+	size_t ignore_footer)
 {
+	struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
 	struct trailer_info info;
-	int i;
+	size_t i;
 	int found_sob = 0, found_sob_last = 0;
 
-	trailer_info_get(&info, sb->buf);
+	opts.no_divider = 1;
+
+	trailer_info_get(&info, sb->buf, &opts);
 
 	if (info.trailer_start == info.trailer_end)
 		return 0;
@@ -3829,7 +3832,7 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 	return res;
 }
 
-void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
+void append_signoff(struct strbuf *msgbuf, size_t ignore_footer, unsigned flag)
 {
 	unsigned no_dup_sob = flag & APPEND_SIGNOFF_DEDUP;
 	struct strbuf sob = STRBUF_INIT;
diff --git a/sequencer.h b/sequencer.h
index c751c9d6e4..c986bc8251 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -90,7 +90,14 @@ int rearrange_squash(void);
 
 extern const char sign_off_header[];
 
-void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag);
+/*
+ * Append a signoff to the commit message in "msgbuf". The ignore_footer
+ * parameter specifies the number of bytes at the end of msgbuf that should
+ * not be considered at all. I.e., they are not checked for existing trailers,
+ * and the new signoff will be spliced into the buffer before those bytes.
+ */
+void append_signoff(struct strbuf *msgbuf, size_t ignore_footer, unsigned flag);
+
 void append_conflicts_hint(struct strbuf *msgbuf);
 int message_is_empty(const struct strbuf *sb,
 		     enum commit_msg_cleanup_mode cleanup_mode);
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 2052cadb11..978a8a66ff 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -598,4 +598,27 @@ test_expect_success ':only and :unfold work together' '
 	test_cmp expect actual
 '
 
+test_expect_success 'trailer parsing not fooled by --- line' '
+	git commit --allow-empty -F - <<-\EOF &&
+	this is the subject
+
+	This is the body. The message has a "---" line which would confuse a
+	message+patch parser. But here we know we have only a commit message,
+	so we get it right.
+
+	trailer: wrong
+	---
+	This is more body.
+
+	trailer: right
+	EOF
+
+	{
+		echo "trailer: right" &&
+		echo
+	} >expect &&
+	git log --no-walk --format="%(trailers)" >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 024f8c06f7..97bfbee6e8 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -715,6 +715,29 @@ test_expect_success 'basic atom: head contents:trailers' '
 	test_cmp expect actual.clean
 '
 
+test_expect_success 'trailer parsing not fooled by --- line' '
+	git commit --allow-empty -F - <<-\EOF &&
+	this is the subject
+
+	This is the body. The message has a "---" line which would confuse a
+	message+patch parser. But here we know we have only a commit message,
+	so we get it right.
+
+	trailer: wrong
+	---
+	This is more body.
+
+	trailer: right
+	EOF
+
+	{
+		echo "trailer: right" &&
+		echo
+	} >expect &&
+	git for-each-ref --format="%(trailers)" refs/heads/master >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'Add symbolic ref for the following tests' '
 	git symbolic-ref refs/heads/sym refs/heads/master
 '
diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 4cae92804d..1a6773ee68 100755
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -517,6 +517,22 @@ Myfooter: x" &&
 	test_cmp expected actual
 '
 
+test_expect_success 'signoff not confused by ---' '
+	cat >expected <<-EOF &&
+		subject
+
+		body
+		---
+		these dashes confuse the parser!
+
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	# should be a noop, since we already signed
+	git commit --allow-empty --signoff -F expected &&
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'multiple -m' '
 
 	>negative &&
diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 164719d1c9..c441861331 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -1417,4 +1417,46 @@ test_expect_success 'unfold' '
 	test_cmp expected actual
 '
 
+test_expect_success 'handling of --- lines in input' '
+	echo "real-trailer: just right" >expected &&
+
+	git interpret-trailers --parse >actual <<-\EOF &&
+	subject
+
+	body
+
+	not-a-trailer: too soon
+	------ this is just a line in the commit message with a bunch of
+	------ dashes; it does not have any syntactic meaning.
+
+	real-trailer: just right
+	---
+	below the dashed line may be a patch, etc.
+
+	not-a-trailer: too late
+	EOF
+
+	test_cmp expected actual
+'
+
+test_expect_success 'suppress --- handling' '
+	echo "real-trailer: just right" >expected &&
+
+	git interpret-trailers --parse --no-divider >actual <<-\EOF &&
+	subject
+
+	This commit message has a "---" in it, but because we tell
+	interpret-trailers not to respect that, it has no effect.
+
+	not-a-trailer: too soon
+	---
+
+	This is still the commit message body.
+
+	real-trailer: just right
+	EOF
+
+	test_cmp expected actual
+'
+
 test_done
diff --git a/trailer.c b/trailer.c
index 4e309460d1..0796f326b3 100644
--- a/trailer.c
+++ b/trailer.c
@@ -585,7 +585,7 @@ static const char *token_from_item(struct arg_item *item, char *tok)
 	return item->conf.name;
 }
 
-static int token_matches_item(const char *tok, struct arg_item *item, int tok_len)
+static int token_matches_item(const char *tok, struct arg_item *item, size_t tok_len)
 {
 	if (!strncasecmp(tok, item->conf.name, tok_len))
 		return 1;
@@ -603,7 +603,7 @@ static int token_matches_item(const char *tok, struct arg_item *item, int tok_le
  * distinguished from the non-well-formed-line case (in which this function
  * returns -1) because some callers of this function need such a distinction.
  */
-static int find_separator(const char *line, const char *separators)
+static ssize_t find_separator(const char *line, const char *separators)
 {
 	int whitespace_found = 0;
 	const char *c;
@@ -630,10 +630,10 @@ static int find_separator(const char *line, const char *separators)
  */
 static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 			 const struct conf_info **conf, const char *trailer,
-			 int separator_pos)
+			 ssize_t separator_pos)
 {
 	struct arg_item *item;
-	int tok_len;
+	size_t tok_len;
 	struct list_head *pos;
 
 	if (separator_pos != -1) {
@@ -721,7 +721,7 @@ static void process_command_line_args(struct list_head *arg_head,
 	list_for_each(pos, new_trailer_head) {
 		struct new_trailer_item *tr =
 			list_entry(pos, struct new_trailer_item, list);
-		int separator_pos = find_separator(tr->text, cl_separators);
+		ssize_t separator_pos = find_separator(tr->text, cl_separators);
 
 		if (separator_pos == 0) {
 			struct strbuf sb = STRBUF_INIT;
@@ -763,9 +763,9 @@ static const char *next_line(const char *str)
 /*
  * Return the position of the start of the last line. If len is 0, return -1.
  */
-static int last_line(const char *buf, size_t len)
+static ssize_t last_line(const char *buf, size_t len)
 {
-	int i;
+	ssize_t i;
 	if (len == 0)
 		return -1;
 	if (len == 1)
@@ -788,12 +788,14 @@ static int last_line(const char *buf, size_t len)
  * Return the position of the start of the patch or the length of str if there
  * is no patch in the message.
  */
-static int find_patch_start(const char *str)
+static size_t find_patch_start(const char *str)
 {
 	const char *s;
 
 	for (s = str; *s; s = next_line(s)) {
-		if (starts_with(s, "---"))
+		const char *v;
+
+		if (skip_prefix(s, "---", &v) && isspace(*v))
 			return s - str;
 	}
 
@@ -804,10 +806,11 @@ static int find_patch_start(const char *str)
  * Return the position of the first trailer line or len if there are no
  * trailers.
  */
-static int find_trailer_start(const char *buf, size_t len)
+static size_t find_trailer_start(const char *buf, size_t len)
 {
 	const char *s;
-	int end_of_title, l, only_spaces = 1;
+	ssize_t end_of_title, l;
+	int only_spaces = 1;
 	int recognized_prefix = 0, trailer_lines = 0, non_trailer_lines = 0;
 	/*
 	 * Number of possible continuation lines encountered. This will be
@@ -838,7 +841,7 @@ static int find_trailer_start(const char *buf, size_t len)
 	     l = last_line(buf, l)) {
 		const char *bol = buf + l;
 		const char **p;
-		int separator_pos;
+		ssize_t separator_pos;
 
 		if (bol[0] == comment_line_char) {
 			non_trailer_lines += possible_continuation_lines;
@@ -899,14 +902,14 @@ static int find_trailer_start(const char *buf, size_t len)
 }
 
 /* Return the position of the end of the trailers. */
-static int find_trailer_end(const char *buf, size_t len)
+static size_t find_trailer_end(const char *buf, size_t len)
 {
 	return len - ignore_non_trailer(buf, len);
 }
 
 static int ends_with_blank_line(const char *buf, size_t len)
 {
-	int ll = last_line(buf, len);
+	ssize_t ll = last_line(buf, len);
 	if (ll < 0)
 		return 0;
 	return is_blank_line(buf + ll);
@@ -939,17 +942,17 @@ static void unfold_value(struct strbuf *val)
 	strbuf_release(&out);
 }
 
-static int process_input_file(FILE *outfile,
-			      const char *str,
-			      struct list_head *head,
-			      const struct process_trailer_options *opts)
+static size_t process_input_file(FILE *outfile,
+				 const char *str,
+				 struct list_head *head,
+				 const struct process_trailer_options *opts)
 {
 	struct trailer_info info;
 	struct strbuf tok = STRBUF_INIT;
 	struct strbuf val = STRBUF_INIT;
-	int i;
+	size_t i;
 
-	trailer_info_get(&info, str);
+	trailer_info_get(&info, str, opts);
 
 	/* Print lines before the trailers as is */
 	if (!opts->only_trailers)
@@ -1032,7 +1035,7 @@ void process_trailers(const char *file,
 {
 	LIST_HEAD(head);
 	struct strbuf sb = STRBUF_INIT;
-	int trailer_end;
+	size_t trailer_end;
 	FILE *outfile = stdout;
 
 	ensure_configured();
@@ -1066,7 +1069,8 @@ void process_trailers(const char *file,
 	strbuf_release(&sb);
 }
 
-void trailer_info_get(struct trailer_info *info, const char *str)
+void trailer_info_get(struct trailer_info *info, const char *str,
+		      const struct process_trailer_options *opts)
 {
 	int patch_start, trailer_end, trailer_start;
 	struct strbuf **trailer_lines, **ptr;
@@ -1076,7 +1080,11 @@ void trailer_info_get(struct trailer_info *info, const char *str)
 
 	ensure_configured();
 
-	patch_start = find_patch_start(str);
+	if (opts->no_divider)
+		patch_start = strlen(str);
+	else
+		patch_start = find_patch_start(str);
+
 	trailer_end = find_trailer_end(str, patch_start);
 	trailer_start = find_trailer_start(str, trailer_end);
 
@@ -1111,7 +1119,7 @@ void trailer_info_get(struct trailer_info *info, const char *str)
 
 void trailer_info_release(struct trailer_info *info)
 {
-	int i;
+	size_t i;
 	for (i = 0; i < info->trailer_nr; i++)
 		free(info->trailers[i]);
 	free(info->trailers);
@@ -1121,7 +1129,7 @@ static void format_trailer_info(struct strbuf *out,
 				const struct trailer_info *info,
 				const struct process_trailer_options *opts)
 {
-	int i;
+	size_t i;
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold) {
@@ -1132,7 +1140,7 @@ static void format_trailer_info(struct strbuf *out,
 
 	for (i = 0; i < info->trailer_nr; i++) {
 		char *trailer = info->trailers[i];
-		int separator_pos = find_separator(trailer, separators);
+		ssize_t separator_pos = find_separator(trailer, separators);
 
 		if (separator_pos >= 1) {
 			struct strbuf tok = STRBUF_INIT;
@@ -1158,7 +1166,7 @@ void format_trailers_from_commit(struct strbuf *out, const char *msg,
 {
 	struct trailer_info info;
 
-	trailer_info_get(&info, msg);
+	trailer_info_get(&info, msg, opts);
 	format_trailer_info(out, &info, opts);
 	trailer_info_release(&info);
 }
diff --git a/trailer.h b/trailer.h
index 9c10026c35..b997739649 100644
--- a/trailer.h
+++ b/trailer.h
@@ -71,6 +71,7 @@ struct process_trailer_options {
 	int only_trailers;
 	int only_input;
 	int unfold;
+	int no_divider;
 };
 
 #define PROCESS_TRAILER_OPTIONS_INIT {0}
@@ -79,7 +80,8 @@ void process_trailers(const char *file,
 		      const struct process_trailer_options *opts,
 		      struct list_head *new_trailer_head);
 
-void trailer_info_get(struct trailer_info *info, const char *str);
+void trailer_info_get(struct trailer_info *info, const char *str,
+		      const struct process_trailer_options *opts);
 
 void trailer_info_release(struct trailer_info *info);