diff --git a/conn.go b/conn.go
index a689bfee..03a2221d 100644
--- a/conn.go
+++ b/conn.go
@@ -470,14 +470,14 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 		switch arg := arguments[i].(type) {
 		case Encoder:
 			wbuf.WriteInt16(arg.FormatCode())
+		case string:
+			wbuf.WriteInt16(TextFormatCode)
 		default:
 			switch oid {
 			case BoolOid, ByteaOid, Int2Oid, Int4Oid, Int8Oid, Float4Oid, Float8Oid, TimestampTzOid:
 				wbuf.WriteInt16(BinaryFormatCode)
-			case TextOid, VarcharOid, DateOid, TimestampOid:
-				wbuf.WriteInt16(TextFormatCode)
 			default:
-				return SerializationError(fmt.Sprintf("Parameter %d oid %d is not a core type and argument type %T does not implement TextEncoder or BinaryEncoder", i, oid, arg))
+				wbuf.WriteInt16(TextFormatCode)
 			}
 		}
 	}
@@ -492,6 +492,8 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 		switch arg := arguments[i].(type) {
 		case Encoder:
 			err = arg.Encode(wbuf, oid)
+		case string:
+			err = encodeText(wbuf, arguments[i])
 		default:
 			switch oid {
 			case BoolOid:
@@ -517,7 +519,7 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 			case TimestampOid:
 				err = encodeTimestamp(wbuf, arguments[i])
 			default:
-				return SerializationError(fmt.Sprintf("%T is not a core type and it does not implement TextEncoder or BinaryEncoder", arg))
+				return SerializationError(fmt.Sprintf("%T is not a core type and it does not implement Encoder", arg))
 			}
 		}
 		if err != nil {
diff --git a/query_test.go b/query_test.go
index 3d8faa19..e5a8fab4 100644
--- a/query_test.go
+++ b/query_test.go
@@ -272,14 +272,19 @@ func TestQueryEncodeError(t *testing.T) {
 	conn := mustConnect(t, *defaultConnConfig)
 	defer closeConn(t, conn)
 
-	_, err := conn.Query("select $1::integer", "wrong")
-	switch {
-	case err == nil:
-		t.Error("Expected transcode error to return error, but it didn't")
-	case err.Error() == "Expected integer representable in int32, received string wrong":
-		// Correct behavior
-	default:
-		t.Errorf("Expected transcode error, received %v", err)
+	rows, err := conn.Query("select $1::integer", "wrong")
+	if err != nil {
+		t.Errorf("conn.Query failure: %v", err)
+	}
+	defer rows.Close()
+
+	rows.Next()
+
+	if rows.Err() == nil {
+		t.Error("Expected rows.Err() to return error, but it didn't")
+	}
+	if rows.Err().Error() != `ERROR: invalid input syntax for integer: "wrong" (SQLSTATE 22P02)` {
+		t.Error("Expected rows.Err() to return different error:", rows.Err())
 	}
 }
 
@@ -399,6 +404,29 @@ func TestQueryRowCoreBytea(t *testing.T) {
 	ensureConnValid(t, conn)
 }
 
+func TestQueryRowUnknownType(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	sql := "select $1::inet"
+	expected := "127.0.0.1"
+	var actual string
+
+	err := conn.QueryRow(sql, expected).Scan(&actual)
+	if err != nil {
+		t.Errorf("Unexpected failure: %v (sql -> %v)", err, sql)
+	}
+
+	if actual != expected {
+		t.Errorf(`Expected "%v", got "%v" (sql -> %v)`, expected, actual, sql)
+
+	}
+
+	ensureConnValid(t, conn)
+}
+
 func TestQueryRowErrors(t *testing.T) {
 	t.Parallel()
 
diff --git a/stdlib/sql_test.go b/stdlib/sql_test.go
index 670224f2..2abe50d1 100644
--- a/stdlib/sql_test.go
+++ b/stdlib/sql_test.go
@@ -295,6 +295,24 @@ func TestConnQueryFailure(t *testing.T) {
 	}
 }
 
+func TestConnQueryRowUnknownType(t *testing.T) {
+	db := openDB(t)
+	defer closeDB(t, db)
+
+	sql := "select $1::inet"
+	expected := "127.0.0.1"
+	var actual string
+
+	err := db.QueryRow(sql, expected).Scan(&actual)
+	if err != nil {
+		t.Errorf("Unexpected failure: %v (sql -> %v)", err, sql)
+	}
+
+	if actual != expected {
+		t.Errorf(`Expected "%v", got "%v" (sql -> %v)`, expected, actual, sql)
+	}
+}
+
 func TestTransactionLifeCycle(t *testing.T) {
 	db := openDB(t)
 	defer closeDB(t, db)