diff --git a/padding/ansi_x923.go b/padding/ansi_x923.go
index b8a46c5..1323ae4 100644
--- a/padding/ansi_x923.go
+++ b/padding/ansi_x923.go
@@ -17,9 +17,7 @@ func (pad ansiX923Padding) Pad(src []byte) []byte {
 	overhead := pad.BlockSize() - len(src)%pad.BlockSize()
 	ret, out := alias.SliceForAppend(src, overhead)
 	out[overhead-1] = byte(overhead)
-	for i := 0; i < overhead-1; i++ {
-		out[i] = 0
-	}
+	clear(out[:overhead-1])
 	return ret
 }
 
diff --git a/padding/iso9797_m2.go b/padding/iso9797_m2.go
index 2351625..cfec485 100644
--- a/padding/iso9797_m2.go
+++ b/padding/iso9797_m2.go
@@ -21,9 +21,7 @@ func (pad iso9797M2Padding) Pad(src []byte) []byte {
 	overhead := pad.BlockSize() - len(src)%pad.BlockSize()
 	ret, out := alias.SliceForAppend(src, overhead)
 	out[0] = 0x80
-	for i := 1; i < overhead; i++ {
-		out[i] = 0
-	}
+	clear(out[1:overhead])
 	return ret
 }