diff --git a/postgresql/database_test.go b/postgresql/database_test.go
index 8cf79bd54cca5c90e4ae5676c1cf5db73e3f8285..33176789df27333280964b6733a00a9455ab3ad5 100644
--- a/postgresql/database_test.go
+++ b/postgresql/database_test.go
@@ -1916,9 +1916,14 @@ func BenchmarkAppendRawSQL(b *testing.B) {
 		b.Fatal(err)
 	}
 
+	stmt, err := driver.Prepare(`INSERT INTO "artist" ("name") VALUES('Hayao Miyazaki')`)
+	if err != nil {
+		b.Fatal(err)
+	}
+
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		if _, err = driver.Exec(`INSERT INTO "artist" ("name") VALUES('Hayao Miyazaki')`); err != nil {
+		if _, err = stmt.Exec(); err != nil {
 			b.Fatal(err)
 		}
 	}
@@ -1974,9 +1979,14 @@ func BenchmarkAppendTxRawSQL(b *testing.B) {
 		b.Fatal(err)
 	}
 
+	stmt, err := tx.Prepare(`INSERT INTO "artist" ("name") VALUES('Hayao Miyazaki')`)
+	if err != nil {
+		b.Fatal(err)
+	}
+
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		if _, err = tx.Exec(`INSERT INTO "artist" ("name") VALUES('Hayao Miyazaki')`); err != nil {
+		if _, err = stmt.Exec(); err != nil {
 			b.Fatal(err)
 		}
 	}