diff --git a/library/error.c b/library/error.c
index 5a813f1..c993524 100644
--- a/library/error.c
+++ b/library/error.c
@@ -28,6 +28,7 @@
 #if defined(MBEDTLS_ERROR_C) || defined(MBEDTLS_ERROR_STRERROR_DUMMY)
 #include "mbedtls/error.h"
 #include <string.h>
+#include "mbedtls/platform_util.h"
 #endif
 
 #if defined(MBEDTLS_PLATFORM_C)