diff --git a/library/oid.c b/library/oid.c
index 27c455e..891d3cd 100644
--- a/library/oid.c
+++ b/library/oid.c
@@ -31,6 +31,7 @@
 
 #include "mbedtls/oid.h"
 #include "mbedtls/rsa.h"
+#include "mbedtls/error.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -732,7 +733,7 @@
 int mbedtls_oid_get_numeric_string( char *buf, size_t size,
                             const mbedtls_asn1_buf *oid )
 {
-    int ret;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t i, n;
     unsigned int value;
     char *p;