diff --git a/Documentation/config/advice.txt b/Documentation/config/advice.txt
index 0e35ae5240..fa61241756 100644
--- a/Documentation/config/advice.txt
+++ b/Documentation/config/advice.txt
@@ -96,6 +96,8 @@ advice.*::
 		`pushNonFFCurrent`, `pushNonFFMatching`, `pushAlreadyExists`,
 		`pushFetchFirst`, `pushNeedsForce`, and `pushRefNeedsUpdate`
 		simultaneously.
+	rebaseTodoError::
+		Shown when there is an error after editing the rebase todo list.
 	refSyntax::
 		Shown when the user provides an illegal ref name, to
 		tell the user about the ref syntax documentation.
diff --git a/advice.c b/advice.c
index d19648b7f8..6546231e91 100644
--- a/advice.c
+++ b/advice.c
@@ -69,6 +69,7 @@ static struct {
 	[ADVICE_PUSH_UNQUALIFIED_REF_NAME]		= { "pushUnqualifiedRefName" },
 	[ADVICE_PUSH_UPDATE_REJECTED]			= { "pushUpdateRejected" },
 	[ADVICE_PUSH_UPDATE_REJECTED_ALIAS]		= { "pushNonFastForward" }, /* backwards compatibility */
+	[ADVICE_REBASE_TODO_ERROR]			= { "rebaseTodoError" },
 	[ADVICE_REF_SYNTAX]				= { "refSyntax" },
 	[ADVICE_RESET_NO_REFRESH_WARNING]		= { "resetNoRefresh" },
 	[ADVICE_RESOLVE_CONFLICT]			= { "resolveConflict" },
diff --git a/advice.h b/advice.h
index c8d29f97f3..5105d90129 100644
--- a/advice.h
+++ b/advice.h
@@ -37,6 +37,7 @@ enum advice_type {
 	ADVICE_PUSH_UNQUALIFIED_REF_NAME,
 	ADVICE_PUSH_UPDATE_REJECTED,
 	ADVICE_PUSH_UPDATE_REJECTED_ALIAS,
+	ADVICE_REBASE_TODO_ERROR,
 	ADVICE_REF_SYNTAX,
 	ADVICE_RESET_NO_REFRESH_WARNING,
 	ADVICE_RESOLVE_CONFLICT,
diff --git a/sequencer.c b/sequencer.c
index a3154ba334..0959f335f7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2573,7 +2573,61 @@ static int check_label_or_ref_arg(enum todo_command command, const char *arg)
 	return 0;
 }
 
-static int parse_insn_line(struct repository *r, struct replay_opts *opts UNUSED,
+static int check_merge_commit_insn(enum todo_command command)
+{
+	switch(command) {
+	case TODO_PICK:
+		error(_("'%s' does not accept merge commits"),
+		      todo_command_info[command].str);
+		advise_if_enabled(ADVICE_REBASE_TODO_ERROR, _(
+			/*
+			 * TRANSLATORS: 'pick' and 'merge -C' should not be
+			 * translated.
+			 */
+			"'pick' does not take a merge commit. If you wanted to\n"
+			"replay the merge, use 'merge -C' on the commit."));
+		return -1;
+
+	case TODO_REWORD:
+		error(_("'%s' does not accept merge commits"),
+		      todo_command_info[command].str);
+		advise_if_enabled(ADVICE_REBASE_TODO_ERROR, _(
+			/*
+			 * TRANSLATORS: 'reword' and 'merge -c' should not be
+			 * translated.
+			 */
+			"'reword' does not take a merge commit. If you wanted to\n"
+			"replay the merge and reword the commit message, use\n"
+			"'merge -c' on the commit"));
+		return -1;
+
+	case TODO_EDIT:
+		error(_("'%s' does not accept merge commits"),
+		      todo_command_info[command].str);
+		advise_if_enabled(ADVICE_REBASE_TODO_ERROR, _(
+			/*
+			 * TRANSLATORS: 'edit', 'merge -C' and 'break' should
+			 * not be translated.
+			 */
+			"'edit' does not take a merge commit. If you wanted to\n"
+			"replay the merge, use 'merge -C' on the commit, and then\n"
+			"'break' to give the control back to you so that you can\n"
+			"do 'git commit --amend && git rebase --continue'."));
+		return -1;
+
+	case TODO_FIXUP:
+	case TODO_SQUASH:
+		return error(_("cannot squash merge commit into another commit"));
+
+	case TODO_MERGE:
+		return 0;
+
+	default:
+		BUG("unexpected todo_command");
+	}
+}
+
+static int parse_insn_line(struct repository *r, struct replay_opts *opts,
 			   struct todo_item *item, const char *buf,
 			   const char *bol, char *eol)
 {
@@ -2679,7 +2733,12 @@ static int parse_insn_line(struct repository *r, struct replay_opts *opts UNUSED
 		return status;
 
 	item->commit = lookup_commit_reference(r, &commit_oid);
-	return item->commit ? 0 : -1;
+	if (!item->commit)
+		return -1;
+	if (is_rebase_i(opts) &&
+	    item->commit->parents && item->commit->parents->next)
+		return check_merge_commit_insn(item->command);
+	return 0;
 }
 
 int sequencer_get_last_command(struct repository *r UNUSED, enum replay_action *action)
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index d1bead61fa..f92baad138 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -2215,6 +2215,51 @@ test_expect_success 'bad labels and refs rejected when parsing todo list' '
 	test_path_is_missing execed
 '
 
+test_expect_success 'non-merge commands reject merge commits' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout E &&
+	git merge I &&
+	oid=$(git rev-parse HEAD) &&
+	cat >todo <<-EOF &&
+	pick $oid
+	reword $oid
+	edit $oid
+	fixup $oid
+	squash $oid
+	EOF
+	(
+		set_replace_editor todo &&
+		test_must_fail git rebase -i HEAD 2>actual
+	) &&
+	cat >expect <<-EOF &&
+	error: ${SQ}pick${SQ} does not accept merge commits
+	hint: ${SQ}pick${SQ} does not take a merge commit. If you wanted to
+	hint: replay the merge, use ${SQ}merge -C${SQ} on the commit.
+	hint: Disable this message with "git config advice.rebaseTodoError false"
+	error: invalid line 1: pick $oid
+	error: ${SQ}reword${SQ} does not accept merge commits
+	hint: ${SQ}reword${SQ} does not take a merge commit. If you wanted to
+	hint: replay the merge and reword the commit message, use
+	hint: ${SQ}merge -c${SQ} on the commit
+	hint: Disable this message with "git config advice.rebaseTodoError false"
+	error: invalid line 2: reword $oid
+	error: ${SQ}edit${SQ} does not accept merge commits
+	hint: ${SQ}edit${SQ} does not take a merge commit. If you wanted to
+	hint: replay the merge, use ${SQ}merge -C${SQ} on the commit, and then
+	hint: ${SQ}break${SQ} to give the control back to you so that you can
+	hint: do ${SQ}git commit --amend && git rebase --continue${SQ}.
+	hint: Disable this message with "git config advice.rebaseTodoError false"
+	error: invalid line 3: edit $oid
+	error: cannot squash merge commit into another commit
+	error: invalid line 4: fixup $oid
+	error: cannot squash merge commit into another commit
+	error: invalid line 5: squash $oid
+	You can fix this with ${SQ}git rebase --edit-todo${SQ} and then run ${SQ}git rebase --continue${SQ}.
+	Or you can abort the rebase with ${SQ}git rebase --abort${SQ}.
+	EOF
+	test_cmp expect actual
+'
+
 # This must be the last test in this file
 test_expect_success '$EDITOR and friends are unchanged' '
 	test_editor_unchanged