diff --git a/bindings/javascript/src/lib.rs b/bindings/javascript/src/lib.rs
index 2c9f874ef..7a8ed46c1 100644
--- a/bindings/javascript/src/lib.rs
+++ b/bindings/javascript/src/lib.rs
@@ -726,7 +726,7 @@ impl turso_core::DatabaseStorage for DatabaseFile {
     fn size(&self) -> turso_core::Result<u64> {
         self.file.size()
     }
-    fn truncate(&self, len: usize, c: turso_core::Completion) -> turso_core::Result<()> {
+    fn truncate(&self, len: usize, c: Arc<turso_core::Completion>) -> turso_core::Result<()> {
         let _ = self.file.truncate(len, c)?;
         Ok(())
     }
diff --git a/bindings/wasm/lib.rs b/bindings/wasm/lib.rs
index 40bafe9b5..2e9e49984 100644
--- a/bindings/wasm/lib.rs
+++ b/bindings/wasm/lib.rs
@@ -264,12 +264,12 @@ impl turso_core::File for File {
     fn truncate(
         &self,
         len: usize,
-        c: turso_core::Completion,
+        c: Arc<turso_core::Completion>,
     ) -> Result<Arc<turso_core::Completion>> {
-        self.vfs.truncate(self.fd, len as usize);
+        self.vfs.truncate(self.fd, len);
         c.complete(0);
         #[allow(clippy::arc_with_non_send_sync)]
-        Ok(Arc::new(c))
+        Ok(c)
     }
 }
 
@@ -391,7 +391,7 @@ impl turso_core::DatabaseStorage for DatabaseFile {
         self.file.size()
     }
 
-    fn truncate(&self, len: usize, c: turso_core::Completion) -> Result<()> {
+    fn truncate(&self, len: usize, c: Arc<turso_core::Completion>) -> Result<()> {
         self.file.truncate(len, c)?;
         Ok(())
     }
diff --git a/core/io/generic.rs b/core/io/generic.rs
index 005de9553..cb70ea068 100644
--- a/core/io/generic.rs
+++ b/core/io/generic.rs
@@ -121,12 +121,12 @@ impl File for GenericFile {
         Ok(c)
     }
 
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         let mut file = self.file.borrow_mut();
         file.set_len(len as u64)
             .map_err(|err| LimboError::IOError(err))?;
         c.complete(0);
-        Ok(Arc::new(c))
+        Ok(c)
     }
 
     fn size(&self) -> Result<u64> {
diff --git a/core/io/io_uring.rs b/core/io/io_uring.rs
index be8083032..4b02aa516 100644
--- a/core/io/io_uring.rs
+++ b/core/io/io_uring.rs
@@ -354,14 +354,13 @@ impl File for UringFile {
         Ok(self.file.metadata()?.len())
     }
 
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         let mut io = self.io.borrow_mut();
         let truncate = with_fd!(self, |fd| {
             io_uring::opcode::Ftruncate::new(fd, len as u64)
                 .build()
                 .user_data(io.ring.get_key())
         });
-        let c = Arc::new(c);
         io.ring.submit_entry(&truncate, c.clone());
         Ok(c)
     }
diff --git a/core/io/memory.rs b/core/io/memory.rs
index ee9903801..df9161453 100644
--- a/core/io/memory.rs
+++ b/core/io/memory.rs
@@ -174,7 +174,7 @@ impl File for MemoryFile {
         Ok(c)
     }
 
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         if len < self.size.get() {
             // Truncate pages
             unsafe {
@@ -184,7 +184,7 @@ impl File for MemoryFile {
         }
         self.size.set(len);
         c.complete(0);
-        Ok(Arc::new(c))
+        Ok(c)
     }
 
     fn size(&self) -> Result<u64> {
diff --git a/core/io/unix.rs b/core/io/unix.rs
index a98943836..0d388044b 100644
--- a/core/io/unix.rs
+++ b/core/io/unix.rs
@@ -452,10 +452,9 @@ impl File for UnixFile<'_> {
     }
 
     #[instrument(err, skip_all, level = Level::INFO)]
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         let file = self.file.borrow();
         let result = file.set_len(len as u64);
-        let c = Arc::new(c);
         match result {
             Ok(()) => {
                 trace!("file truncated to len=({})", len);
diff --git a/core/io/vfs.rs b/core/io/vfs.rs
index 50873636e..25a52263a 100644
--- a/core/io/vfs.rs
+++ b/core/io/vfs.rs
@@ -166,7 +166,7 @@ impl File for VfsFileImpl {
         }
     }
 
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         if self.vfs.is_null() {
             return Err(LimboError::ExtensionError("VFS is null".to_string()));
         }
@@ -176,7 +176,7 @@ impl File for VfsFileImpl {
             Err(LimboError::ExtensionError("truncate failed".to_string()))
         } else {
             c.complete(0);
-            Ok(Arc::new(c))
+            Ok(c)
         }
     }
 }
diff --git a/core/io/windows.rs b/core/io/windows.rs
index 418faf59f..2ae910b9b 100644
--- a/core/io/windows.rs
+++ b/core/io/windows.rs
@@ -123,11 +123,11 @@ impl File for WindowsFile {
     }
 
     #[instrument(err, skip_all, level = Level::TRACE)]
-    fn truncate(&self, len: usize, c: Completion) -> Result<Arc<Completion>> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
         let mut file = self.file.borrow_mut();
         file.set_len(len as u64).map_err(LimboError::IOError)?;
         c.complete(0);
-        Ok(())
+        Ok(c)
     }
 
     fn size(&self) -> Result<u64> {
diff --git a/core/storage/database.rs b/core/storage/database.rs
index 17f17439b..c7560f8fe 100644
--- a/core/storage/database.rs
+++ b/core/storage/database.rs
@@ -18,7 +18,7 @@ pub trait DatabaseStorage: Send + Sync {
     ) -> Result<Completion>;
     fn sync(&self, c: Completion) -> Result<Completion>;
     fn size(&self) -> Result<u64>;
-    fn truncate(&self, len: usize, c: Completion) -> Result<()>;
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<()>;
 }
 
 #[cfg(feature = "fs")]
@@ -72,7 +72,7 @@ impl DatabaseStorage for DatabaseFile {
     }
 
     #[instrument(skip_all, level = Level::INFO)]
-    fn truncate(&self, len: usize, c: Completion) -> Result<()> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<()> {
         self.file.truncate(len, c)?;
         Ok(())
     }
@@ -131,7 +131,7 @@ impl DatabaseStorage for FileMemoryStorage {
     }
 
     #[instrument(skip_all, level = Level::INFO)]
-    fn truncate(&self, len: usize, c: Completion) -> Result<()> {
+    fn truncate(&self, len: usize, c: Arc<Completion>) -> Result<()> {
         let _ = self.file.truncate(len, c)?;
         Ok(())
     }
diff --git a/core/storage/wal.rs b/core/storage/wal.rs
index e1cea6635..9cb997f9f 100644
--- a/core/storage/wal.rs
+++ b/core/storage/wal.rs
@@ -17,7 +17,7 @@ use std::{
 };
 
 use crate::fast_lock::SpinLock;
-use crate::io::{CompletionType, File, IO};
+use crate::io::{File, IO};
 use crate::result::LimboResult;
 use crate::storage::sqlite3_ondisk::{
     begin_read_wal_frame, begin_read_wal_frame_raw, finish_read_page, prepare_wal_frame,
@@ -1345,10 +1345,7 @@ impl WalFileShared {
 
 #[cfg(test)]
 pub mod test {
-    use crate::{
-        storage::sqlite3_ondisk::WAL_HEADER_SIZE, Completion, CompletionType, Database, MemoryIO,
-        IO,
-    };
+    use crate::{storage::sqlite3_ondisk::WAL_HEADER_SIZE, Completion, Database, MemoryIO, IO};
     use std::{cell::Cell, rc::Rc, sync::Arc};
     use tempfile::TempDir;
 
@@ -1380,12 +1377,10 @@ pub mod test {
         let _done = done.clone();
         let _ = file.file.truncate(
             WAL_HEADER_SIZE,
-            Completion::new(CompletionType::Truncate(
-                crate::io::TruncateCompletion::new(Box::new(move |_| {
-                    let done = _done.clone();
-                    done.set(true);
-                })),
-            )),
+            Arc::new(Completion::new_trunc(move |_| {
+                let done = _done.clone();
+                done.set(true);
+            })),
         );
         assert!(file.file.size().unwrap() == WAL_HEADER_SIZE as u64);
         assert!(done.get());
diff --git a/simulator/runner/file.rs b/simulator/runner/file.rs
index f78ae3287..928b51d5a 100644
--- a/simulator/runner/file.rs
+++ b/simulator/runner/file.rs
@@ -229,33 +229,24 @@ impl File for SimulatorFile {
     fn truncate(
         &self,
         len: usize,
-        mut c: turso_core::Completion,
+        c: Arc<turso_core::Completion>,
     ) -> Result<Arc<turso_core::Completion>> {
         if self.fault.get() {
             return Err(turso_core::LimboError::InternalError(
                 FAULT_ERROR_MSG.into(),
             ));
         }
-        if let Some(latency) = self.generate_latency_duration() {
-            let CompletionType::Truncate(truncate_completion) = &mut c.completion_type else {
-                unreachable!();
-            };
-            let before = self.rng.borrow_mut().gen_bool(0.5);
-            let dummy_complete = Box::new(|_| {});
-            let prev_complete =
-                std::mem::replace(&mut truncate_completion.complete, dummy_complete);
-            let new_complete = move |res| {
-                if before {
-                    std::thread::sleep(latency);
-                }
-                (prev_complete)(res);
-                if !before {
-                    std::thread::sleep(latency);
-                }
-            };
-            truncate_completion.complete = Box::new(new_complete);
+        let c = if let Some(latency) = self.generate_latency_duration() {
+            let cloned_c = c.clone();
+            let op = Box::new(move |file: &SimulatorFile| file.inner.truncate(len, cloned_c));
+            self.queued_io
+                .borrow_mut()
+                .push(DelayedIo { time: latency, op });
+            c
+        } else {
+            self.inner.truncate(len, c)?
         };
-        self.inner.truncate(len, c)
+        Ok(c)
     }
 }