diff --git a/internal/hammer/ddl.go b/internal/hammer/ddl.go
index b607945..4539f27 100644
--- a/internal/hammer/ddl.go
+++ b/internal/hammer/ddl.go
@@ -57,8 +57,10 @@ func (u Update) defaultValue() string {
 		return "false"
 	case spansql.Int64, spansql.Float64:
 		return "0"
-	case spansql.String, spansql.Bytes:
+	case spansql.String:
 		return "''"
+	case spansql.Bytes:
+		return "b''"
 	case spansql.Date:
 		return "'0001-01-01'"
 	case spansql.Timestamp:
diff --git a/internal/hammer/ddl_test.go b/internal/hammer/ddl_test.go
index f629448..b167fc6 100644
--- a/internal/hammer/ddl_test.go
+++ b/internal/hammer/ddl_test.go
@@ -60,6 +60,10 @@ func TestUpdate_SQL(t *testing.T) {
 			d: spansql.ColumnDef{Name: "test_column", Type: spansql.Type{Base: spansql.String}},
 			s: "UPDATE test_table SET test_column = '' WHERE test_column IS NULL",
 		},
+		{
+			d: spansql.ColumnDef{Name: "test_column", Type: spansql.Type{Base: spansql.Bytes}},
+			s: "UPDATE test_table SET test_column = b'' WHERE test_column IS NULL",
+		},
 		{
 			d: spansql.ColumnDef{Name: "test_column", Type: spansql.Type{Base: spansql.String, Array: true}},
 			s: "UPDATE test_table SET test_column = [] WHERE test_column IS NULL",