diff --git a/pkg/core/dao/dao.go b/pkg/core/dao/dao.go
index 48a4e5f56..88a0b9981 100644
--- a/pkg/core/dao/dao.go
+++ b/pkg/core/dao/dao.go
@@ -537,7 +537,7 @@ func (dao *Simple) GetHeaderHashes() ([]util.Uint256, error) {
 	for k := range hashMap {
 		sortedKeys = append(sortedKeys, k)
 	}
-	sort.Sort(slice(sortedKeys))
+	sort.Slice(sortedKeys, func(i, j int) bool { return sortedKeys[i] < sortedKeys[j] })
 
 	for _, key := range sortedKeys {
 		hashes = append(hashes[:key], hashMap[key]...)
diff --git a/pkg/core/dao/uint32.go b/pkg/core/dao/uint32.go
deleted file mode 100644
index d1a79057b..000000000
--- a/pkg/core/dao/uint32.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package dao
-
-// slice attaches the methods of Interface to []int, sorting in increasing order.
-type slice []uint32
-
-func (p slice) Len() int           { return len(p) }
-func (p slice) Less(i, j int) bool { return p[i] < p[j] }
-func (p slice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }