diff --git a/library/x509_crt.c b/library/x509_crt.c
index a3a4525..6728fa0 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -26,6 +26,7 @@
 #include "mbedtls/oid.h"
 #include "mbedtls/platform_util.h"
 
+#include <limits.h>
 #include <string.h>
 
 #if defined(MBEDTLS_PEM_PARSE_C)