diff --git a/library/sha1.c b/library/sha1.c
index 355c83d..9233943 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -34,6 +34,7 @@
 
 #include "mbedtls/sha1.h"
 #include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
 
 #include <string.h>
 
@@ -307,7 +308,7 @@
                              const unsigned char *input,
                              size_t ilen )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t fill;
     uint32_t left;
 
@@ -368,7 +369,7 @@
 int mbedtls_sha1_finish_ret( mbedtls_sha1_context *ctx,
                              unsigned char output[20] )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     uint32_t used;
     uint32_t high, low;
 
@@ -440,7 +441,7 @@
                       size_t ilen,
                       unsigned char output[20] )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_sha1_context ctx;
 
     SHA1_VALIDATE_RET( ilen == 0 || input != NULL );