diff --git a/bpchar.go b/bpchar.go
index f82e3724..e4d058e9 100644
--- a/bpchar.go
+++ b/bpchar.go
@@ -33,6 +33,10 @@ func (src *BPChar) AssignTo(dst interface{}) error {
 	return (*Text)(src).AssignTo(dst)
 }
 
+func (BPChar) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *BPChar) DecodeText(ci *ConnInfo, src []byte) error {
 	return (*Text)(dst).DecodeText(ci, src)
 }
@@ -41,6 +45,10 @@ func (dst *BPChar) DecodeBinary(ci *ConnInfo, src []byte) error {
 	return (*Text)(dst).DecodeBinary(ci, src)
 }
 
+func (BPChar) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src BPChar) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	return (Text)(src).EncodeText(ci, buf)
 }
diff --git a/enum_type.go b/enum_type.go
index 6f52817a..1a6a4b46 100644
--- a/enum_type.go
+++ b/enum_type.go
@@ -128,6 +128,10 @@ func (src *enumType) AssignTo(dst interface{}) error {
 	return errors.Errorf("cannot decode %#v into %T", src, dst)
 }
 
+func (enumType) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *enumType) DecodeText(ci *ConnInfo, src []byte) error {
 	if src == nil {
 		dst.status = Null
@@ -152,6 +156,10 @@ func (dst *enumType) DecodeBinary(ci *ConnInfo, src []byte) error {
 	return dst.DecodeText(ci, src)
 }
 
+func (enumType) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src enumType) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	switch src.status {
 	case Null:
diff --git a/json.go b/json.go
index c642c727..922da50d 100644
--- a/json.go
+++ b/json.go
@@ -113,6 +113,10 @@ func (src *JSON) AssignTo(dst interface{}) error {
 	return nil
 }
 
+func (JSON) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *JSON) DecodeText(ci *ConnInfo, src []byte) error {
 	if src == nil {
 		*dst = JSON{Status: Null}
@@ -127,6 +131,10 @@ func (dst *JSON) DecodeBinary(ci *ConnInfo, src []byte) error {
 	return dst.DecodeText(ci, src)
 }
 
+func (JSON) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src JSON) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	switch src.Status {
 	case Null:
diff --git a/jsonb.go b/jsonb.go
index 984c0973..c129ac9b 100644
--- a/jsonb.go
+++ b/jsonb.go
@@ -20,6 +20,10 @@ func (src *JSONB) AssignTo(dst interface{}) error {
 	return (*JSON)(src).AssignTo(dst)
 }
 
+func (JSONB) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *JSONB) DecodeText(ci *ConnInfo, src []byte) error {
 	return (*JSON)(dst).DecodeText(ci, src)
 }
@@ -43,6 +47,10 @@ func (dst *JSONB) DecodeBinary(ci *ConnInfo, src []byte) error {
 
 }
 
+func (JSONB) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src JSONB) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	return (JSON)(src).EncodeText(ci, buf)
 }
diff --git a/pgtype.go b/pgtype.go
index 7c893360..ed676929 100644
--- a/pgtype.go
+++ b/pgtype.go
@@ -142,6 +142,18 @@ type TypeValue interface {
 	TypeName() string
 }
 
+// ResultFormatPreferrer allows a type to specify its preferred result format instead of it being inferred from
+// whether it is also a BinaryDecoder.
+type ResultFormatPreferrer interface {
+	PreferredResultFormat() int16
+}
+
+// ParamFormatPreferrer allows a type to specify its preferred param format instead of it being inferred from
+// whether it is also a BinaryEncoder.
+type ParamFormatPreferrer interface {
+	PreferredParamFormat() int16
+}
+
 type BinaryDecoder interface {
 	// DecodeBinary decodes src into BinaryDecoder. If src is nil then the
 	// original SQL value is NULL. BinaryDecoder takes ownership of src. The
@@ -364,7 +376,9 @@ func (ci *ConnInfo) RegisterDataType(t DataType) {
 
 	{
 		var formatCode int16
-		if _, ok := t.Value.(BinaryEncoder); ok {
+		if pfp, ok := t.Value.(ParamFormatPreferrer); ok {
+			formatCode = pfp.PreferredParamFormat()
+		} else if _, ok := t.Value.(BinaryEncoder); ok {
 			formatCode = BinaryFormatCode
 		}
 		ci.oidToParamFormatCode[t.OID] = formatCode
@@ -372,7 +386,9 @@ func (ci *ConnInfo) RegisterDataType(t DataType) {
 
 	{
 		var formatCode int16
-		if _, ok := t.Value.(BinaryDecoder); ok {
+		if rfp, ok := t.Value.(ResultFormatPreferrer); ok {
+			formatCode = rfp.PreferredResultFormat()
+		} else if _, ok := t.Value.(BinaryDecoder); ok {
 			formatCode = BinaryFormatCode
 		}
 		ci.oidToResultFormatCode[t.OID] = formatCode
diff --git a/pgtype_test.go b/pgtype_test.go
index e1c49666..a96720d5 100644
--- a/pgtype_test.go
+++ b/pgtype_test.go
@@ -44,6 +44,26 @@ func mustParseMacaddr(t testing.TB, s string) net.HardwareAddr {
 	return addr
 }
 
+func TestConnInfoResultFormatCodeForOID(t *testing.T) {
+	ci := pgtype.NewConnInfo()
+
+	// pgtype.JSONB implements BinaryDecoder but also implements ResultFormatPreferrer to override it to text.
+	assert.Equal(t, int16(pgtype.TextFormatCode), ci.ResultFormatCodeForOID(pgtype.JSONBOID))
+
+	// pgtype.Int4 implements BinaryDecoder but does not implement ResultFormatPreferrer so it should be binary.
+	assert.Equal(t, int16(pgtype.BinaryFormatCode), ci.ResultFormatCodeForOID(pgtype.Int4OID))
+}
+
+func TestConnInfoParamFormatCodeForOID(t *testing.T) {
+	ci := pgtype.NewConnInfo()
+
+	// pgtype.JSONB implements BinaryEncoder but also implements ParamFormatPreferrer to override it to text.
+	assert.Equal(t, int16(pgtype.TextFormatCode), ci.ParamFormatCodeForOID(pgtype.JSONBOID))
+
+	// pgtype.Int4 implements BinaryEncoder but does not implement ParamFormatPreferrer so it should be binary.
+	assert.Equal(t, int16(pgtype.BinaryFormatCode), ci.ParamFormatCodeForOID(pgtype.Int4OID))
+}
+
 func TestConnInfoScanUnknownOIDToStringsAndBytes(t *testing.T) {
 	unknownOID := uint32(999999)
 	srcBuf := []byte("foo")
diff --git a/text.go b/text.go
index 1f5d2a37..4c9e4a21 100644
--- a/text.go
+++ b/text.go
@@ -85,6 +85,10 @@ func (src *Text) AssignTo(dst interface{}) error {
 	return errors.Errorf("cannot decode %#v into %T", src, dst)
 }
 
+func (Text) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *Text) DecodeText(ci *ConnInfo, src []byte) error {
 	if src == nil {
 		*dst = Text{Status: Null}
@@ -99,6 +103,10 @@ func (dst *Text) DecodeBinary(ci *ConnInfo, src []byte) error {
 	return dst.DecodeText(ci, src)
 }
 
+func (Text) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src Text) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	switch src.Status {
 	case Null:
diff --git a/varchar.go b/varchar.go
index e4fa6869..fea31d18 100644
--- a/varchar.go
+++ b/varchar.go
@@ -23,6 +23,10 @@ func (src *Varchar) AssignTo(dst interface{}) error {
 	return (*Text)(src).AssignTo(dst)
 }
 
+func (Varchar) PreferredResultFormat() int16 {
+	return TextFormatCode
+}
+
 func (dst *Varchar) DecodeText(ci *ConnInfo, src []byte) error {
 	return (*Text)(dst).DecodeText(ci, src)
 }
@@ -31,6 +35,10 @@ func (dst *Varchar) DecodeBinary(ci *ConnInfo, src []byte) error {
 	return (*Text)(dst).DecodeBinary(ci, src)
 }
 
+func (Varchar) PreferredParamFormat() int16 {
+	return TextFormatCode
+}
+
 func (src Varchar) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 	return (Text)(src).EncodeText(ci, buf)
 }