diff --git a/credentials/alts/internal/conn/record.go b/credentials/alts/internal/conn/record.go
index f9d2646d4b22..329e3691f0d5 100644
--- a/credentials/alts/internal/conn/record.go
+++ b/credentials/alts/internal/conn/record.go
@@ -68,7 +68,9 @@ const (
 	// altsRecordDefaultLength.
 	altsWriteBufferMaxSize = 512 * 1024 // 512KiB
 	// The initial buffer used to read from the network.
-	altsReadBufferInitialSize = 32 * 1024 // 32KiB
+	// It includes an additional 512 Bytes to hold two 16KiB records plus
+	// small framing overheads.
+	altsReadBufferInitialSize = 32*1024 + 512 // 32.5KiB
 )
 
 var (