diff --git a/go.mod b/go.mod
index 00679e12..075b4ee9 100644
--- a/go.mod
+++ b/go.mod
@@ -9,6 +9,7 @@ require (
 	github.com/lib/pq v1.1.0
 	github.com/satori/go.uuid v1.2.0
 	github.com/shopspring/decimal v0.0.0-20180709203117-cd690d0c9e24
+	github.com/stretchr/testify v1.3.0
 	go.uber.org/atomic v1.3.2 // indirect
 	go.uber.org/multierr v1.1.0 // indirect
 	golang.org/x/xerrors v0.0.0-20190410155217-1f06c39b4373
diff --git a/go.sum b/go.sum
index ecd3007e..919c31c3 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,6 @@
 github.com/cockroachdb/apd v1.1.0/go.mod h1:8Sl8LxpKi29FqWXR16WEFZRNSz3SoPzUzeMeY4+DwBQ=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/jackc/chunkreader v1.0.0 h1:4s39bBR8ByfqH+DKm8rQA3E1LHZWB9XWcrz8fqaZbe0=
 github.com/jackc/chunkreader v1.0.0/go.mod h1:RT6O25fNZIuasFJRyZ4R/Y2BbhasbmZXF9QQ7T3kePo=
@@ -28,6 +29,7 @@ github.com/lib/pq v1.1.0 h1:/5u4a+KGJptBRqGzPvYQL9p0d/tPR4S31+Tnzj9lEO4=
 github.com/lib/pq v1.1.0/go.mod h1:5WUZQaWbwv1U+lTReE5YruASi9Al49XbQIvNi/34Woo=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rs/zerolog v1.13.0/go.mod h1:YbFCdg8HfsridGWAh22vktObvhZbQsZXe4/zB0OKkWU=
 github.com/satori/go.uuid v1.2.0 h1:0uYX9dsZ2yD7q2RtLRtPSdGDWzjeM3TbMJP9utgA0ww=
@@ -38,6 +40,7 @@ github.com/sirupsen/logrus v1.4.1/go.mod h1:ni0Sbl8bgC9z8RoU9G6nDWqqs/fq4eDPysMB
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 go.uber.org/atomic v1.3.2/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
diff --git a/pgtype.go b/pgtype.go
index cea4e1cd..94e8bcbc 100644
--- a/pgtype.go
+++ b/pgtype.go
@@ -342,7 +342,27 @@ func (ci *ConnInfo) Scan(oid OID, formatCode int16, buf []byte, dest interface{}
 			return value.AssignTo(dest)
 		}
 	}
-	return errors.Errorf("unknown oid: %v", oid)
+
+	return scanUnknownType(oid, formatCode, buf, dest)
+}
+
+func scanUnknownType(oid OID, formatCode int16, buf []byte, dest interface{}) error {
+	switch dest := dest.(type) {
+	case *string:
+		if formatCode == BinaryFormatCode {
+			return errors.Errorf("unknown oid %d in binary format cannot be scanned into %t", oid, dest)
+		}
+		*dest = string(buf)
+		return nil
+	case *[]byte:
+		*dest = buf
+		return nil
+	default:
+		if nextDst, retry := GetAssignToDstType(dest); retry {
+			return scanUnknownType(oid, formatCode, buf, nextDst)
+		}
+		return errors.Errorf("unknown oid %d cannot be scanned into %t", oid, dest)
+	}
 }
 
 var nameValues map[string]Value
diff --git a/pgtype_test.go b/pgtype_test.go
index 400c0591..53580d18 100644
--- a/pgtype_test.go
+++ b/pgtype_test.go
@@ -4,8 +4,11 @@ import (
 	"net"
 	"testing"
 
+	"github.com/jackc/pgtype"
+	"github.com/jackc/pgx/v4"
 	_ "github.com/jackc/pgx/v4/stdlib"
 	_ "github.com/lib/pq"
+	"github.com/stretchr/testify/assert"
 )
 
 // Test for renamed types
@@ -37,3 +40,37 @@ func mustParseMacaddr(t testing.TB, s string) net.HardwareAddr {
 
 	return addr
 }
+
+func TestConnInfoScanUnknownOID(t *testing.T) {
+	unknownOID := pgtype.OID(999999)
+	srcBuf := []byte("foo")
+	ci := pgtype.NewConnInfo()
+
+	var s string
+	err := ci.Scan(unknownOID, pgx.TextFormatCode, srcBuf, &s)
+	assert.NoError(t, err)
+	assert.Equal(t, "foo", s)
+
+	var rs _string
+	err = ci.Scan(unknownOID, pgx.TextFormatCode, srcBuf, &rs)
+	assert.NoError(t, err)
+	assert.Equal(t, "foo", string(rs))
+
+	var b []byte
+	err = ci.Scan(unknownOID, pgx.TextFormatCode, srcBuf, &b)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("foo"), b)
+
+	err = ci.Scan(unknownOID, pgx.BinaryFormatCode, srcBuf, &b)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("foo"), b)
+
+	var rb _byteSlice
+	err = ci.Scan(unknownOID, pgx.TextFormatCode, srcBuf, &rb)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("foo"), []byte(rb))
+
+	err = ci.Scan(unknownOID, pgx.BinaryFormatCode, srcBuf, &b)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("foo"), []byte(rb))
+}