diff --git a/spanner/value.go b/spanner/value.go
index 3f806f8b7657..8e75dfc15987 100644
--- a/spanner/value.go
+++ b/spanner/value.go
@@ -2718,7 +2718,7 @@ func (dsc decodableSpannerType) decodeValueToCustomType(v *proto3.Value, t *sppb
 			result = &NullString{x, !isNull}
 		}
 	case spannerTypeByteArray:
-		if code != sppb.TypeCode_BYTES {
+		if code != sppb.TypeCode_BYTES && code != sppb.TypeCode_PROTO {
 			return errTypeMismatch(code, acode, ptr)
 		}
 		if isNull {
@@ -2735,7 +2735,7 @@ func (dsc decodableSpannerType) decodeValueToCustomType(v *proto3.Value, t *sppb
 		}
 		result = y
 	case spannerTypeNonNullInt64, spannerTypeNullInt64:
-		if code != sppb.TypeCode_INT64 {
+		if code != sppb.TypeCode_INT64 && code != sppb.TypeCode_ENUM {
 			return errTypeMismatch(code, acode, ptr)
 		}
 		if isNull {
@@ -2913,7 +2913,7 @@ func (dsc decodableSpannerType) decodeValueToCustomType(v *proto3.Value, t *sppb
 		}
 		result = y
 	case spannerTypeArrayOfByteArray:
-		if acode != sppb.TypeCode_BYTES {
+		if acode != sppb.TypeCode_BYTES && acode != sppb.TypeCode_PROTO {
 			return errTypeMismatch(code, acode, ptr)
 		}
 		if isNull {
@@ -2930,7 +2930,7 @@ func (dsc decodableSpannerType) decodeValueToCustomType(v *proto3.Value, t *sppb
 		}
 		result = y
 	case spannerTypeArrayOfNonNullInt64, spannerTypeArrayOfNullInt64:
-		if acode != sppb.TypeCode_INT64 {
+		if acode != sppb.TypeCode_INT64 && acode != sppb.TypeCode_ENUM {
 			return errTypeMismatch(code, acode, ptr)
 		}
 		if isNull {
diff --git a/spanner/value_test.go b/spanner/value_test.go
index 95d12643c812..6e7ac34c6f61 100644
--- a/spanner/value_test.go
+++ b/spanner/value_test.go
@@ -18,6 +18,7 @@ package spanner
 
 import (
 	"bytes"
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -3289,3 +3290,74 @@ func TestNullJson(t *testing.T) {
 		t.Fatalf("expected null, got %s", v)
 	}
 }
+
+// Test decode for PROTO type when custom type is a variant of a base type
+func TestDecodeProtoUsingBaseVariant(t *testing.T) {
+	// nullBytes is custom type from []byte base type.
+	type nullBytes []byte
+
+	var b []byte
+	var nb nullBytes
+
+	gcv := &GenericColumnValue{
+		Type: &sppb.Type{
+			Code:         sppb.TypeCode_PROTO,
+			ProtoTypeFqn: "examples.ProtoType",
+		},
+		Value: structpb.NewStringValue("Zm9vCg=="),
+	}
+	if err := gcv.Decode(&nb); err != nil {
+		t.Error(err)
+	}
+	if err := gcv.Decode(&b); err != nil {
+		t.Error(err)
+	}
+
+	// Convert []byte and nullBytes to base64 encoding and then compare the contents.
+	if !testutil.Equal(base64.StdEncoding.EncodeToString(b), base64.StdEncoding.EncodeToString(nb)) {
+		t.Errorf("%s: got %+v, want %+v", "Test PROTO decode to []byte custom type", nb, b)
+	}
+}
+
+// Test decode for PROTO type when custom type is a variant of a base type
+func TestDecodeProtoArrayUsingBaseVariant(t *testing.T) {
+	// nullBytes is custom type from []byte base type.
+	type nullBytes [][]byte
+
+	var b [][]byte
+	var nb nullBytes
+
+	gcv := &GenericColumnValue{
+		Type: &sppb.Type{
+			Code: sppb.TypeCode_ARRAY,
+			ArrayElementType: &sppb.Type{
+				Code:         sppb.TypeCode_PROTO,
+				ProtoTypeFqn: "examples.ProtoType",
+			},
+		},
+		Value: structpb.NewListValue(
+			&structpb.ListValue{
+				Values: []*structpb.Value{
+					structpb.NewStringValue("Zm9vCg=="),
+				},
+			}),
+	}
+	if err := gcv.Decode(&nb); err != nil {
+		t.Error(err)
+	}
+	if err := gcv.Decode(&b); err != nil {
+		t.Error(err)
+	}
+
+	if len(b) != 1 {
+		t.Errorf("Expected length to be 1")
+	}
+
+	if len(nb) != 1 {
+		t.Errorf("Expected length to be 1")
+	}
+	// Convert to base64 encoding and then compare the contents.
+	if !testutil.Equal(base64.StdEncoding.EncodeToString(b[0]), base64.StdEncoding.EncodeToString(nb[0])) {
+		t.Errorf("%s: got %+v, want %+v", "Test PROTO decode to [][]byte custom type", nb, b)
+	}
+}