diff --git a/library/gcm.c b/library/gcm.c
index 5121a7a..26f6010 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -39,6 +39,7 @@
 
 #include "mbedtls/gcm.h"
 #include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
 
 #include <string.h>
 
@@ -168,7 +169,7 @@
                         const unsigned char *key,
                         unsigned int keybits )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     const mbedtls_cipher_info_t *cipher_info;
 
     GCM_VALIDATE_RET( ctx != NULL );
@@ -280,7 +281,7 @@
                 const unsigned char *add,
                 size_t add_len )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char work_buf[16];
     size_t i;
     const unsigned char *p;
@@ -365,7 +366,7 @@
                 const unsigned char *input,
                 unsigned char *output )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char ectr[16];
     size_t i;
     const unsigned char *p;
@@ -476,7 +477,7 @@
                        size_t tag_len,
                        unsigned char *tag )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     GCM_VALIDATE_RET( ctx != NULL );
     GCM_VALIDATE_RET( iv != NULL );
@@ -508,7 +509,7 @@
                       const unsigned char *input,
                       unsigned char *output )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char check_tag[16];
     size_t i;
     int diff;