-

diff --git a/modules/host/contractmanager/dependencies.go b/modules/host/contractmanager/dependencies.go
index abbd23d..2508e2c 100644
--- a/modules/host/contractmanager/dependencies.go
+++ b/modules/host/contractmanager/dependencies.go
@@ -89,6 +89,7 @@ type (
 		Sync() error
 		Truncate(int64) error
 		WriteAt([]byte, int64) (int, error)
+		Fd() uintptr
 	}
 )
 
diff --git a/modules/host/contractmanager/sector.go b/modules/host/contractmanager/sector.go
index f8ba8ba..3553c34 100644
--- a/modules/host/contractmanager/sector.go
+++ b/modules/host/contractmanager/sector.go
@@ -5,10 +5,12 @@ import (
 	"errors"
 	"sync"
 	"sync/atomic"
+	"syscall"
 
 	"github.com/NebulousLabs/Sia/build"
 	"github.com/NebulousLabs/Sia/crypto"
 	"github.com/NebulousLabs/Sia/modules"
+	"golang.org/x/sys/unix"
 )
 
 var (
@@ -94,6 +96,17 @@ func writeSector(f file, sectorIndex uint32, data []byte) error {
 	return nil
 }
 
+// deallocateSector will clear the region of the file trying to make
+// the disk space free.
+func deallocateSector(f file, sectorIndex uint32) error {
+	return syscall.Fallocate(
+		int(f.Fd()),
+		unix.FALLOC_FL_PUNCH_HOLE | unix.FALLOC_FL_KEEP_SIZE,
+		int64(uint64(sectorIndex)*modules.SectorSize),
+		int64(modules.SectorSize),
+	)
+}
+
 // writeSectorMetadata will take a sector update and write the related metadata
 // to disk.
 func writeSectorMetadata(f file, sectorIndex uint32, id sectorID, count uint16) error {
diff --git a/modules/host/contractmanager/sectorupdate.go b/modules/host/contractmanager/sectorupdate.go
index 808996e..80f08de 100644
--- a/modules/host/contractmanager/sectorupdate.go
+++ b/modules/host/contractmanager/sectorupdate.go
@@ -23,6 +23,7 @@ func (wal *writeAheadLog) commitUpdateSector(su sectorUpdate) {
 	// If the sector is being cleaned from disk, unset the usage flag.
 	if su.Count == 0 {
 		sf.clearUsage(su.Index)
+		_ = deallocateSector(sf.sectorFile, su.Index)
 		return
 	}
 
@@ -99,6 +100,7 @@ func (wal *writeAheadLog) managedAddPhysicalSector(id sectorID, data []byte, cou
 				sf.clearUsage(sectorIndex)
 				delete(sf.availableSectors, id)
 				wal.mu.Unlock()
+				_ = deallocateSector(sf.sectorFile, sectorIndex)
 				return errDiskTrouble
 			}
 
@@ -117,6 +119,7 @@ func (wal *writeAheadLog) managedAddPhysicalSector(id sectorID, data []byte, cou
 				sf.clearUsage(sectorIndex)
 				delete(sf.availableSectors, id)
 				wal.mu.Unlock()
+				_ = deallocateSector(sf.sectorFile, sectorIndex)
 				return errDiskTrouble
 			}
 
@@ -265,6 +268,7 @@ func (wal *writeAheadLog) managedDeleteSector(id sectorID) error {
 	delete(sf.availableSectors, id)
 	sf.clearUsage(location.index)
 	wal.mu.Unlock()
+	_ = deallocateSector(sf.sectorFile, location.index)
 	return nil
 }
 
@@ -349,6 +353,7 @@ func (wal *writeAheadLog) managedRemoveSector(id sectorID) error {
 		sf.clearUsage(location.index)
 		delete(sf.availableSectors, id)
 		wal.mu.Unlock()
+		_ = deallocateSector(sf.sectorFile, location.index)
 	}
 	return nil
 }