diff --git a/lib/hx509/crypto-ec.c b/lib/hx509/crypto-ec.c
index ea7a50d0a..bd5d01a60 100644
--- a/lib/hx509/crypto-ec.c
+++ b/lib/hx509/crypto-ec.c
@@ -41,6 +41,7 @@
 #include <openssl/bn.h>
 #include <openssl/objects.h>
 #ifdef HAVE_OPENSSL_30
+#include <openssl/asn1.h>
 #include <openssl/core_names.h>
 #endif
 #define HEIM_NO_CRYPTO_HDRS