diff --git a/graphdriver/devmapper/devmapper.go b/graphdriver/devmapper/devmapper.go
index 4ba995754..de82bde0f 100644
--- a/graphdriver/devmapper/devmapper.go
+++ b/graphdriver/devmapper/devmapper.go
@@ -47,7 +47,6 @@ var (
 	ErrTaskAddTarget          = errors.New("dm_task_add_target failed")
 	ErrTaskSetSector          = errors.New("dm_task_set_sector failed")
 	ErrTaskGetInfo            = errors.New("dm_task_get_info failed")
-	ErrTaskGetDriverVersion   = errors.New("dm_task_get_driver_version failed")
 	ErrTaskSetCookie          = errors.New("dm_task_set_cookie failed")
 	ErrNilCookie              = errors.New("cookie ptr can't be nil")
 	ErrAttachLoopbackDevice   = errors.New("loopback mounting failed")
diff --git a/graphdriver/devmapper/devmapper_test.go b/graphdriver/devmapper/devmapper_test.go
index 33167f095..8fd234cba 100644
--- a/graphdriver/devmapper/devmapper_test.go
+++ b/graphdriver/devmapper/devmapper_test.go
@@ -246,10 +246,6 @@ func dmTaskAddTargetFail(task *CDmTask,
 	return -1
 }
 
-func dmTaskGetDriverVersionFail(task *CDmTask, version *string) int {
-	return -1
-}
-
 func dmTaskGetInfoFail(task *CDmTask, info *Info) int {
 	return -1
 }
@@ -267,10 +263,6 @@ func sysGetBlockSizeFail(fd uintptr, size *uint64) sysErrno {
 	return 1
 }
 
-func dmGetBlockSizeFail(fd uintptr) int64 {
-	return -1
-}
-
 func dmUdevWaitFail(cookie uint) int {
 	return -1
 }