diff --git a/CHANGELOG.md b/CHANGELOG.md
index a703a6dfe2..5dd93ce4ab 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * Revsets now support `\`-escapes in string literal.
 
+* Fixed a bug with `jj split` introduced in 0.16.0 that caused it to incorrectly
+  rebase the children of the revision being split if they had other parents
+  (i.e. if the child was a merge).
 
 ## [0.16.0] - 2024-04-03
 
diff --git a/cli/src/commands/split.rs b/cli/src/commands/split.rs
index 0cec68fc2d..af83bfda07 100644
--- a/cli/src/commands/split.rs
+++ b/cli/src/commands/split.rs
@@ -19,9 +19,10 @@ use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::revset::{RevsetExpression, RevsetIteratorExt};
 use jj_lib::rewrite::merge_commit_trees;
+use jj_lib::settings::UserSettings;
 use tracing::instrument;
 
-use crate::cli_util::{CommandHelper, RevisionArg};
+use crate::cli_util::{CommandHelper, RevisionArg, WorkspaceCommandTransaction};
 use crate::command_error::CommandError;
 use crate::commands::rebase::rebase_descendants;
 use crate::description_util::{description_template_for_commit, edit_description};
@@ -176,25 +177,17 @@ the operation will be aborted.
     // commit.
     tx.mut_repo()
         .set_rewritten_commit(commit.id().clone(), second_commit.id().clone());
-    // Rebase descendants of the commit being split.
-    let new_parents = if args.siblings {
-        vec![first_commit.clone(), second_commit.clone()]
+    let num_rebased = if args.siblings {
+        rebase_children_for_siblings_split(
+            &mut tx,
+            command.settings(),
+            &commit,
+            vec![first_commit.clone(), second_commit.clone()],
+        )?
     } else {
-        vec![second_commit.clone()]
+        tx.mut_repo().rebase_descendants(command.settings())?
     };
-    let children: Vec<Commit> = RevsetExpression::commit(commit.id().clone())
-        .children()
-        .evaluate_programmatic(tx.base_repo().as_ref())?
-        .iter()
-        .commits(tx.base_repo().store())
-        .try_collect()?;
-    let num_rebased = rebase_descendants(
-        &mut tx,
-        command.settings(),
-        &new_parents,
-        &children,
-        Default::default(),
-    )?;
+
     if let Some(mut formatter) = ui.status_formatter() {
         if num_rebased > 0 {
             writeln!(formatter, "Rebased {num_rebased} descendant commits")?;
@@ -208,3 +201,37 @@ the operation will be aborted.
     tx.finish(ui, format!("split commit {}", commit.id().hex()))?;
     Ok(())
 }
+
+// Rebases the children of `original_commit` by replacing `original_commit` with
+// `new_siblings`. Any parents other than `original_commit` will remain after
+// the rebase.
+fn rebase_children_for_siblings_split(
+    tx: &mut WorkspaceCommandTransaction,
+    settings: &UserSettings,
+    original_commit: &Commit,
+    new_siblings: Vec<Commit>,
+) -> Result<usize, CommandError> {
+    let children: Vec<Commit> = RevsetExpression::commit(original_commit.id().clone())
+        .children()
+        .evaluate_programmatic(tx.base_repo().as_ref())?
+        .iter()
+        .commits(tx.base_repo().store())
+        .try_collect()?;
+    let mut num_rebased = 0;
+    for child in children {
+        let new_parents = child
+            .parents()
+            .into_iter()
+            .flat_map(|c| {
+                if c.id() == original_commit.id() {
+                    new_siblings.clone()
+                } else {
+                    vec![c]
+                }
+            })
+            .collect_vec();
+        num_rebased +=
+            rebase_descendants(tx, settings, &new_parents, &[child], Default::default())?;
+    }
+    Ok(num_rebased)
+}
diff --git a/cli/tests/test_split_command.rs b/cli/tests/test_split_command.rs
index 35be5f7276..81bc878140 100644
--- a/cli/tests/test_split_command.rs
+++ b/cli/tests/test_split_command.rs
@@ -377,3 +377,50 @@ JJ: Lines starting with "JJ: " (like this one) will be removed.
     ◉  zzzzzzzzzzzz true
     "###);
 }
+
+// This test makes sure that the children of the commit being split retain any
+// other parents which weren't involved in the split.
+#[test]
+fn test_split_siblings_with_merge_child() {
+    let mut test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["init", "repo", "--git"]);
+    let workspace_path = test_env.env_root().join("repo");
+    test_env.jj_cmd_ok(&workspace_path, &["describe", "-m=1"]);
+    test_env.jj_cmd_ok(&workspace_path, &["new", "root()", "-m=a"]);
+    std::fs::write(workspace_path.join("file1"), "foo\n").unwrap();
+    std::fs::write(workspace_path.join("file2"), "bar\n").unwrap();
+    test_env.jj_cmd_ok(
+        &workspace_path,
+        &["new", "description(1)", "description(a)", "-m=2"],
+    );
+    insta::assert_snapshot!(get_log_output(&test_env, &workspace_path), @r###"
+    @    zsuskulnrvyr true 2
+    ├─╮
+    │ ◉  kkmpptxzrspx false a
+    ◉ │  qpvuntsmwlqt true 1
+    ├─╯
+    ◉  zzzzzzzzzzzz true
+    "###);
+
+    // Set up the editor and do the split.
+    let edit_script = test_env.set_up_fake_editor();
+    std::fs::write(
+        edit_script,
+        ["write\nAdd file1", "next invocation\n", "write\nAdd file2"].join("\0"),
+    )
+    .unwrap();
+    test_env.jj_cmd_ok(
+        &workspace_path,
+        &["split", "-r", "description(a)", "--siblings", "file1"],
+    );
+    insta::assert_snapshot!(get_log_output(&test_env, &workspace_path), @r###"
+    @      zsuskulnrvyr true 2
+    ├─┬─╮
+    │ │ ◉  royxmykxtrkr false Add file2
+    │ ◉ │  kkmpptxzrspx false Add file1
+    │ ├─╯
+    ◉ │  qpvuntsmwlqt true 1
+    ├─╯
+    ◉  zzzzzzzzzzzz true
+    "###);
+}