diff --git a/src/trees-plugin.h b/src/trees-plugin.h
index c6fd36e..d3da04f 100644
--- a/src/trees-plugin.h
+++ b/src/trees-plugin.h
@@ -33,9 +33,11 @@ trees_pluging_pwhash_map(int value)
 	case 0:
 		/* argon2i, libsodium <= 1.0.14. */
 		return crypto_pwhash_ALG_ARGON2I13;
+#ifdef crypto_pwhash_ALG_ARGON2IDI3
 	case 1:
 		/* argon2id, libsodium >= 1.0.15 */
 		return crypto_pwhash_ALG_ARGON2ID13;
+#endif
 	default:
 		return -1;
 	}