diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h
index a04a145..0b26727 100644
--- a/include/mbedtls/bignum.h
+++ b/include/mbedtls/bignum.h
@@ -25,7 +25,7 @@
 #define MBEDTLS_BIGNUM_H
 
 #if !defined(MBEDTLS_CONFIG_FILE)
-#include "config.h"
+#include "mbedtls/config.h"
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif