diff --git a/lib/hcrypto/ecdh.h b/lib/hcrypto/ecdh.h
index 71b94a2fc..4dda28499 100644
--- a/lib/hcrypto/ecdh.h
+++ b/lib/hcrypto/ecdh.h
@@ -38,6 +38,7 @@
 
 #include <hcrypto/ec.h>
 
+int
 ECDH_compute_key(void *, size_t,
 		 const EC_KEY *, const EC_KEY *,
 		 void *(*KDF)(const void *, size_t, void *, size_t *));