diff --git a/spanner/row.go b/spanner/row.go
index 0e3f216ab50..8097031e2de 100644
--- a/spanner/row.go
+++ b/spanner/row.go
@@ -58,6 +58,8 @@ import (
 //	*[]bool, *[]NullBool - BOOL ARRAY
 //	*float64(not NULL), *NullFloat64 - FLOAT64
 //	*[]float64, *[]NullFloat64 - FLOAT64 ARRAY
+//	*big.Rat(not NULL), *NullNumeric - NUMERIC
+//	*[]big.Rat, *[]NullNumeric - NUMERIC ARRAY
 //	*time.Time(not NULL), *NullTime - TIMESTAMP
 //	*[]time.Time, *[]NullTime - TIMESTAMP ARRAY
 //	*Date(not NULL), *NullDate - DATE