diff --git a/library/pkwrite.c b/library/pkwrite.c
index f5630f3..3c1a408 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -517,7 +517,7 @@
         end = PEM_END_PRIVATE_KEY_RSA;
     } else
 #endif
-#if defined(MBEDTLS_ECP_C)
+#if defined(MBEDTLS_ECP_LIGHT)
     if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
         begin = PEM_BEGIN_PRIVATE_KEY_EC;
         end = PEM_END_PRIVATE_KEY_EC;