diff --git a/common-algo.c b/common-algo.c
index 88633677a8f3a678d8428bcdfa6cd7db65aeab23..892399fee191b1d97a5149e534962bdbcacc3cc3 100644
--- a/common-algo.c
+++ b/common-algo.c
@@ -31,7 +31,9 @@
 
 static int void_cipher(const unsigned char* in, unsigned char* out,
 		unsigned long len, void *cipher_state) {
-	memcpy(out, in, len);
+	if (in != out) {
+		memmove(out, in, len);
+	}
 	return CRYPT_OK;
 }