diff --git a/js/models/core/TxProposals.js b/js/models/core/TxProposals.js
index 2481b3a72..9e33d6eab 100644
--- a/js/models/core/TxProposals.js
+++ b/js/models/core/TxProposals.js
@@ -45,9 +45,7 @@ TxProposals.prototype.getNtxids = function() {
 };
 
 TxProposals.prototype.deleteOne = function(ntxid) {
-  var txp = this.txps[ntxid];
-  if (!txp)
-    throw new Error('Unknown TXP: ' + ntxid);
+  preconditions.checkState(this.txps[ntxid], 'Unknown TXP: ' + ntxid);
   delete this.txps[ntxid];
 };
 
diff --git a/test/test.TxProposals.js b/test/test.TxProposals.js
index a7a25e727..f94435f48 100644
--- a/test/test.TxProposals.js
+++ b/test/test.TxProposals.js
@@ -65,6 +65,21 @@ describe('TxProposals', function() {
       txps.getNtxids().should.deep.equal(['a','b']);
     });
   });
+  describe.only('#deleteOne', function() {
+    it('should delete specified ntxid', function() {
+      var txps = new TxProposals();
+      txps.txps = {a:1, b:2};
+      txps.deleteOne('a');
+      txps.getNtxids().should.deep.equal(['b']);
+    });
+    it('should fail on non-existent ntxid', function() {
+      var txps = new TxProposals();
+      txps.txps = {a:1, b:2};
+      (function () {
+        txps.deleteOne('c');
+      }).should.throw('Unknown TXP: c');
+    });
+  });
   describe('#toObj', function() {
     it('should an object', function() {
       var txps = TxProposals.fromObj({