diff --git a/library/chacha20.c b/library/chacha20.c
index 8a3610f..343b216 100644
--- a/library/chacha20.c
+++ b/library/chacha20.c
@@ -33,6 +33,7 @@
 
 #include "mbedtls/chacha20.h"
 #include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
 
 #include <stddef.h>
 #include <string.h>
@@ -325,7 +326,7 @@
                             unsigned char* output )
 {
     mbedtls_chacha20_context ctx;
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     CHACHA20_VALIDATE_RET( key != NULL );
     CHACHA20_VALIDATE_RET( nonce != NULL );
@@ -536,7 +537,7 @@
 {
     unsigned char output[381];
     unsigned i;
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     for( i = 0U; i < 2U; i++ )
     {