diff --git a/src/ecpubkey.js b/src/ecpubkey.js
index 026be2b..db4c07c 100644
--- a/src/ecpubkey.js
+++ b/src/ecpubkey.js
@@ -10,10 +10,10 @@ var sec = require('./sec')
 var ecparams = sec('secp256k1')
 
 function ECPubKey(Q, compressed) {
-  assert(Q instanceof ECPointFp, 'Q must be an ECPointFP')
+  assert(Q instanceof ECPointFp, 'Expected ECPointFP, got ' + Q)
 
   if (compressed == undefined) compressed = true
-  assert.strictEqual(typeof compressed, 'boolean', 'Invalid compression flag')
+  assert.strictEqual(typeof compressed, 'boolean', 'Expected boolean, got ' + compressed)
 
   this.compressed = compressed
   this.Q = Q
diff --git a/src/script.js b/src/script.js
index 8ee030b..cce5189 100644
--- a/src/script.js
+++ b/src/script.js
@@ -247,7 +247,7 @@ Script.prototype.writeOp = function(opcode) {
 Script.prototype.writeBytes = function(data) {
   // FIXME: Script module doesn't support buffers yet
   if (Buffer.isBuffer(data)) data = Array.prototype.slice.call(data);
-  assert(Array.isArray(data), "Expected a byte array. Got " + data)
+  assert(Array.isArray(data), 'Expected a byte array, got ' + data)
 
   if (data.length < opcodes.OP_PUSHDATA1) {
     this.buffer.push(data.length)
@@ -305,7 +305,7 @@ Script.createP2SHScriptPubKey = function(hash) {
 
 // m [pubKeys ...] n OP_CHECKMULTISIG
 Script.createMultisigScriptPubKey = function(m, pubKeys) {
-  assert(Array.isArray(pubKeys), 'Expected Array, got: ' + pubKeys)
+  assert(Array.isArray(pubKeys), 'Expected Array, got ' + pubKeys)
   assert(pubKeys.length >= m, 'Not enough pubKeys provided')
   var script = new Script()
   var n = pubKeys.length
@@ -369,7 +369,7 @@ Script.prototype.clone = function() {
 }
 
 Script.fromChunks = function(chunks) {
-  assert(Array.isArray(chunks), 'Expected Array, got: ' + chunks)
+  assert(Array.isArray(chunks), 'Expected Array, got ' + chunks)
 
   var bufferSize = chunks.reduce(function(accum, chunk) {
     var chunkSize = 1