diff --git a/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/down.sql b/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/down.sql
new file mode 100644
index 0000000..acf93a6
--- /dev/null
+++ b/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/down.sql
@@ -0,0 +1,24 @@
+CREATE TABLE messages_new (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    message_id TEXT NOT NULL,
+    subject TEXT NOT NULL,
+    folder_id INTEGER NOT NULL,
+    time_received TIMESTAMP NOT NULL,
+    "from" TEXT NOT NULL,
+    "to" TEXT NOT NULL,
+    cc TEXT NOT NULL,
+    bcc TEXT NOT NULL,
+    content TEXT,
+    "references" TEXT NOT NULL,
+    in_reply_to TEXT NOT NULL,
+    uid INTEGER NOT NULL,
+    modification_sequence INTEGER NOT NULL,
+    seen BOOLEAN NOT NULL,
+    flagged BOOLEAN NOT NULL,
+    draft BOOLEAN NOT NULL,
+    deleted BOOLEAN NOT NULL
+);
+
+INSERT INTO messages_new SELECT * FROM messages;
+DROP TABLE messages;
+ALTER TABLE messages_new RENAME TO messages;
\ No newline at end of file
diff --git a/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/up.sql b/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/up.sql
new file mode 100644
index 0000000..71d7faf
--- /dev/null
+++ b/app/migrations/2023-11-12-160133_make_modification_sequence_nullable/up.sql
@@ -0,0 +1,24 @@
+CREATE TABLE messages_new (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    message_id TEXT NOT NULL,
+    subject TEXT NOT NULL,
+    folder_id INTEGER NOT NULL,
+    time_received TIMESTAMP NOT NULL,
+    "from" TEXT NOT NULL,
+    "to" TEXT NOT NULL,
+    cc TEXT NOT NULL,
+    bcc TEXT NOT NULL,
+    content TEXT,
+    "references" TEXT NOT NULL,
+    in_reply_to TEXT NOT NULL,
+    uid INTEGER NOT NULL,
+    modification_sequence INTEGER NULL,
+    seen BOOLEAN NOT NULL,
+    flagged BOOLEAN NOT NULL,
+    draft BOOLEAN NOT NULL,
+    deleted BOOLEAN NOT NULL
+);
+
+INSERT INTO messages_new SELECT * FROM messages;
+DROP TABLE messages;
+ALTER TABLE messages_new RENAME TO messages;
\ No newline at end of file
diff --git a/app/src/backends/imap/sync.rs b/app/src/backends/imap/sync.rs
index 9bb82bb..368d73a 100644
--- a/app/src/backends/imap/sync.rs
+++ b/app/src/backends/imap/sync.rs
@@ -8,6 +8,7 @@ use melib::MeliError;
 
 use log::debug;
 
+use std::borrow::Cow;
 use std::convert::TryInto;
 use std::time::Instant;
 
@@ -174,8 +175,13 @@ async fn fetch_messages_overview_in_uid_range(
             //     message_sequence_number: 0,
             //     references: None,
 
-            //@TODO conversion from i64 to u64
-            new_message.modification_sequence = message.modseq.unwrap().0.get().try_into().unwrap();
+            new_message.modification_sequence = message
+                .modseq
+                // The DB uses i64 but the backend gives us NonZeroU64 so we have to do this conversion
+                .map(|modseq| TryInto::<i64>::try_into(u64::from(modseq.0)))
+                .transpose()
+                // Abusing the types a little bit to coerce into a valid MeliError
+                .or_else(|_| Err(Cow::from("Unable to convert modification sequence type")))?;
 
             messages_list.push(new_message);
         }
diff --git a/app/src/models/database.rs b/app/src/models/database.rs
index 15833ef..dd818f6 100644
--- a/app/src/models/database.rs
+++ b/app/src/models/database.rs
@@ -38,7 +38,7 @@ pub struct Message {
     pub references: String,
     pub in_reply_to: String,
     pub uid: i64,
-    pub modification_sequence: i64,
+    pub modification_sequence: Option<i64>,
     pub seen: bool,
     pub flagged: bool,
     pub draft: bool,
@@ -153,7 +153,7 @@ pub struct NewMessage {
     pub references: String,
     pub in_reply_to: String,
     pub uid: i64,
-    pub modification_sequence: i64,
+    pub modification_sequence: Option<i64>,
     pub seen: bool,
     pub flagged: bool,
     pub draft: bool,
@@ -179,8 +179,8 @@ impl From<melib::email::Envelope> for NewMessage {
             in_reply_to: envelope
                 .in_reply_to()
                 .map_or("".to_string(), |x| String::from_utf8(x.0.clone()).unwrap()),
-            uid: 0,                   //@TODO
-            modification_sequence: 0, //@TODO
+            uid: 0, //@TODO
+            modification_sequence: Some(0),
             seen: flags.contains(melib::email::Flag::SEEN),
             flagged: flags.contains(melib::email::Flag::FLAGGED),
             draft: flags.contains(melib::email::Flag::DRAFT),
diff --git a/app/src/schema.rs b/app/src/schema.rs
index dea0eb1..cd1dfbb 100644
--- a/app/src/schema.rs
+++ b/app/src/schema.rs
@@ -57,7 +57,7 @@ table! {
         references -> Text,
         in_reply_to -> Text,
         uid -> BigInt,
-        modification_sequence -> BigInt,
+        modification_sequence -> Nullable<BigInt>,
         seen -> Bool,
         flagged -> Bool,
         draft -> Bool,