diff --git a/dataframe.go b/dataframe.go
index d5d757a..f9bdafe 100644
--- a/dataframe.go
+++ b/dataframe.go
@@ -88,7 +88,7 @@ func (df *DataFrame) Row(row int, dontReadLock bool, retOpt ...SeriesReturnOpt)
 		defer df.lock.RUnlock()
 	}
 
-	out := map[interface{}]interface{}{}
+	out := make(map[interface{}]interface{}, len(df.Series))
 
 	for idx, aSeries := range df.Series {
 		val := aSeries.Value(row)