diff --git a/helix-core/src/history.rs b/helix-core/src/history.rs
index 4a666fbd4160e..862ce1bb5bad8 100644
--- a/helix-core/src/history.rs
+++ b/helix-core/src/history.rs
@@ -189,6 +189,23 @@ impl History {
         Ok((last_saved_revision, history))
     }
 
+    pub fn merge(&mut self, mut other: History, offset: usize) -> std::io::Result<()> {
+        let revisions = self.revisions.split_off(offset);
+        let len = other.revisions.len();
+        for r in revisions {
+            let parent = if r.parent < offset {
+                r.parent
+            } else {
+                len + (r.parent - offset)
+            };
+            other.revisions.get_mut(parent).unwrap().last_child =
+                NonZeroUsize::new(other.revisions.len());
+            other.revisions.push(r);
+        }
+        self.revisions = other.revisions;
+        Ok(())
+    }
+
     pub fn read_header<R: Read>(reader: &mut R, path: &Path) -> std::io::Result<(usize, usize)> {
         let header = read_string(reader)?;
         if HEADER_TAG != header {
@@ -259,6 +276,11 @@ impl History {
         self.current == 0
     }
 
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.revisions.len() <= 1
+    }
+
     /// Returns the changes since the given revision composed into a transaction.
     /// Returns None if there are no changes between the current and given revisions.
     pub fn changes_since(&self, revision: usize) -> Option<Transaction> {
diff --git a/helix-term/src/application.rs b/helix-term/src/application.rs
index f7964162127b0..1c88cba3cd95e 100644
--- a/helix-term/src/application.rs
+++ b/helix-term/src/application.rs
@@ -515,10 +515,6 @@ impl Application {
             }
         };
 
-        if doc_save_event.serialize_error {
-            self.editor.set_error("failed to serialize history");
-        }
-
         let doc = match self.editor.document_mut(doc_save_event.doc_id) {
             None => {
                 warn!(
@@ -570,6 +566,9 @@ impl Application {
             lines,
             bytes
         ));
+        if doc_save_event.serialize_error {
+            self.editor.set_error("failed to serialize history");
+        }
     }
 
     #[inline(always)]
diff --git a/helix-term/tests/test/commands.rs b/helix-term/tests/test/commands.rs
index 44f6978a893eb..2cfe3ac4053e9 100644
--- a/helix-term/tests/test/commands.rs
+++ b/helix-term/tests/test/commands.rs
@@ -486,6 +486,7 @@ async fn test_persistent_undo() -> anyhow::Result<()> {
         .with_file(file.path(), None)
         .build()?;
 
+    // TODO: Test if the history file is valid.
     test_key_sequence(
         &mut app,
         Some(&format!(
diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 9861ad9e6fb41..4b248ad5e4180 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -20,6 +20,7 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::sync::Arc;
 use std::time::SystemTime;
+use tokio::fs::OpenOptions;
 
 use helix_core::{
     encoding,
@@ -591,7 +592,7 @@ impl Document {
             .load()
             .persistent_undo
             .then(|| self.history.get_mut().clone());
-        let undo_file = self.undo_file(Some(&path))?.unwrap();
+        let undofile_path = self.undo_file(Some(&path))?.unwrap();
         // We encode the file according to the `Document`'s encoding.
         let future = async move {
             use tokio::{fs, fs::File};
@@ -624,16 +625,22 @@ impl Document {
             if let Some(history) = history {
                 let res = {
                     let path = path.clone();
+                    let mut undofile = OpenOptions::new()
+                        .write(true)
+                        .read(true)
+                        .create(true)
+                        .open(&undofile_path)
+                        .await?
+                        .into_std()
+                        .await;
                     tokio::task::spawn_blocking(move || -> anyhow::Result<()> {
-                        use std::fs;
                         let append =
-                            History::read_header(&mut fs::File::open(&undo_file)?, &path).is_ok();
-                        let mut undo_file = std::fs::OpenOptions::new()
-                            .write(true)
-                            .truncate(!append)
-                            .read(true)
-                            .open(&undo_file)?;
-                        history.serialize(&mut undo_file, &path, current_rev, append)?;
+                            History::deserialize(&mut std::fs::File::open(&undofile_path)?, &path)
+                                .is_ok();
+                        if !append {
+                            undofile.set_len(0)?;
+                        }
+                        history.serialize(&mut undofile, &path, current_rev, append)?;
                         Ok(())
                     })
                     .await
@@ -717,14 +724,16 @@ impl Document {
         let mut file = std::fs::File::open(&path)?;
         let (rope, ..) = from_reader(&mut file, Some(encoding))?;
 
-        // Calculate the difference between the buffer and source text, and apply it.
-        // This is not considered a modification of the contents of the file regardless
-        // of the encoding.
-        let transaction = helix_core::diff::compare_ropes(self.text(), &rope);
-        self.apply(&transaction, view.id);
-        self.append_changes_to_history(view);
-        self.reset_modified();
-
+        if let Err(e) = self.load_history() {
+            log::error!("{}", e);
+            // Calculate the difference between the buffer and source text, and apply it.
+            // This is not considered a modification of the contents of the file regardless
+            // of the encoding.
+            let transaction = helix_core::diff::compare_ropes(self.text(), &rope);
+            self.apply(&transaction, view.id);
+            self.append_changes_to_history(view);
+            self.reset_modified();
+        }
         self.last_saved_time = SystemTime::now();
 
         self.detect_indent_and_line_ending();
@@ -761,7 +770,13 @@ impl Document {
                     &mut undo_file,
                     self.path().unwrap(),
                 )?;
-                self.history.set(history);
+
+                if self.history.get_mut().is_empty() {
+                    self.history.set(history);
+                } else {
+                    let offset = self.get_last_saved_revision() + 1;
+                    self.history.get_mut().merge(history, offset)?;
+                }
                 self.set_last_saved_revision(last_saved_revision);
             }
         }