diff --git a/reflect/convert.go b/reflect/convert.go
index 3e43fb1..3be00c6 100644
--- a/reflect/convert.go
+++ b/reflect/convert.go
@@ -47,7 +47,7 @@ func ConvertToType(v interface{}, t reflect.Type) (interface{}, error) {
 		switch t.Kind() {
 		case Map:
 			var (
-				res = reflect.MakeMap(t)
+				res = reflect.MakeMapWithSize(t, len(vv.MapKeys()))
 				ck  interface{}
 			)
 			for _, k := range vv.MapKeys() {