diff --git a/lib/bcoin/address.js b/lib/bcoin/address.js
index e20a5459..834b968d 100644
--- a/lib/bcoin/address.js
+++ b/lib/bcoin/address.js
@@ -189,6 +189,8 @@ Address.prototype.getProgram = function getProgram() {
     } else if (this.type === 'multisig') {
       hash = Address.sha256(this.getScript().encode());
       program = bcoin.script.createWitnessProgram(0, hash);
+    } else {
+      assert(false, 'Unknown address type.');
     }
     this._program = program;
   }