diff --git a/library/cipher_wrap.c b/library/cipher_wrap.c
index 7fc40b5..a813426 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -32,6 +32,7 @@
 #if defined(MBEDTLS_CIPHER_C)
 
 #include "mbedtls/cipher_internal.h"
+#include "mbedtls/error.h"
 
 #if defined(MBEDTLS_CHACHAPOLY_C)
 #include "mbedtls/chachapoly.h"
@@ -1916,7 +1917,7 @@
                                  const unsigned char *input,
                                  unsigned char *output )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     ret = mbedtls_chacha20_update( ctx, length, input, output );
     if( ret == MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA )