diff --git a/pgtype.go b/pgtype.go
index 1705ae41..d8dd5abf 100644
--- a/pgtype.go
+++ b/pgtype.go
@@ -179,12 +179,6 @@ 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
@@ -243,7 +237,7 @@ type ConnInfo struct {
 	oidToDataType         map[uint32]*DataType
 	nameToDataType        map[string]*DataType
 	reflectTypeToName     map[reflect.Type]string
-	oidToParamFormatCode  map[uint32]int16
+	oidToFormatCode       map[uint32]int16
 	oidToResultFormatCode map[uint32]int16
 
 	reflectTypeToDataType map[reflect.Type]*DataType
@@ -256,7 +250,7 @@ func newConnInfo() *ConnInfo {
 		oidToDataType:                     make(map[uint32]*DataType),
 		nameToDataType:                    make(map[string]*DataType),
 		reflectTypeToName:                 make(map[reflect.Type]string),
-		oidToParamFormatCode:              make(map[uint32]int16),
+		oidToFormatCode:                   make(map[uint32]int16),
 		oidToResultFormatCode:             make(map[uint32]int16),
 		preferAssignToOverSQLScannerTypes: make(map[reflect.Type]struct{}),
 	}
@@ -392,24 +386,12 @@ func (ci *ConnInfo) RegisterDataType(t DataType) {
 
 	{
 		var formatCode int16
-		if pfp, ok := t.Value.(ParamFormatPreferrer); ok {
-			formatCode = pfp.PreferredParamFormat()
+		if pfp, ok := t.Value.(FormatSupport); ok {
+			formatCode = pfp.PreferredFormat()
 		} else if _, ok := t.Value.(BinaryEncoder); ok {
 			formatCode = BinaryFormatCode
 		}
-		ci.oidToParamFormatCode[t.OID] = formatCode
-	}
-
-	{
-		var formatCode int16
-		if fs, ok := t.Value.(FormatSupport); ok {
-			formatCode = fs.PreferredFormat()
-		} else if rfp, ok := t.Value.(ResultFormatPreferrer); ok {
-			formatCode = rfp.PreferredResultFormat()
-		} else if _, ok := t.Value.(BinaryDecoder); ok {
-			formatCode = BinaryFormatCode
-		}
-		ci.oidToResultFormatCode[t.OID] = formatCode
+		ci.oidToFormatCode[t.OID] = formatCode
 	}
 
 	if d, ok := t.Value.(ResultDecoder); ok {
@@ -477,16 +459,8 @@ func (ci *ConnInfo) DataTypeForValue(v interface{}) (*DataType, bool) {
 	return dt, ok
 }
 
-func (ci *ConnInfo) ParamFormatCodeForOID(oid uint32) int16 {
-	fc, ok := ci.oidToParamFormatCode[oid]
-	if ok {
-		return fc
-	}
-	return TextFormatCode
-}
-
-func (ci *ConnInfo) ResultFormatCodeForOID(oid uint32) int16 {
-	fc, ok := ci.oidToResultFormatCode[oid]
+func (ci *ConnInfo) FormatCodeForOID(oid uint32) int16 {
+	fc, ok := ci.oidToFormatCode[oid]
 	if ok {
 		return fc
 	}
diff --git a/pgtype_test.go b/pgtype_test.go
index 7ae756e5..9bf1f242 100644
--- a/pgtype_test.go
+++ b/pgtype_test.go
@@ -67,24 +67,14 @@ 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) {
+func TestConnInfoFormatCodeForOID(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))
+	assert.Equal(t, int16(pgtype.TextFormatCode), ci.FormatCodeForOID(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))
+	assert.Equal(t, int16(pgtype.BinaryFormatCode), ci.FormatCodeForOID(pgtype.Int4OID))
 }
 
 func TestConnInfoScanNilIsNoOp(t *testing.T) {