diff --git a/lib/script_interpreter.js b/lib/script_interpreter.js
index 3244770..952fc9b 100644
--- a/lib/script_interpreter.js
+++ b/lib/script_interpreter.js
@@ -127,12 +127,12 @@ ScriptInterpreter.castToBool = function(buf) {
 ScriptInterpreter.prototype.checkSignatureEncoding = function(buf) {
   var sig;
   if ((this.flags & (ScriptInterpreter.SCRIPT_VERIFY_DERSIG | ScriptInterpreter.SCRIPT_VERIFY_LOW_S | ScriptInterpreter.SCRIPT_VERIFY_STRICTENC)) !== 0 && !Signature.isTxDER(buf)) {
-    this.errstr = 'SCRIPT_ERR_SIG_DER';
+    this.errstr = 'SCRIPT_ERR_SIG_DER_INVALID_FORMAT';
     return false;
   } else if ((this.flags & ScriptInterpreter.SCRIPT_VERIFY_LOW_S) !== 0) {
-    sig = Signature().fromTxFormat(buf);
+    sig = Signature.fromTxFormat(buf);
     if (!sig.hasLowS()) {
-      this.errstr = 'SCRIPT_ERR_SIG_DER';
+      this.errstr = 'SCRIPT_ERR_SIG_DER_HIGH_S';
       return false;
     }
   } else if ((this.flags & ScriptInterpreter.SCRIPT_VERIFY_STRICTENC) !== 0) {
diff --git a/test/crypto/signature.js b/test/crypto/signature.js
index 77fdefd..9f941bf 100644
--- a/test/crypto/signature.js
+++ b/test/crypto/signature.js
@@ -5,6 +5,7 @@ var bitcore = require('../..');
 var BN = bitcore.crypto.BN;
 var Signature = bitcore.crypto.Signature;
 var JSUtil = bitcore.util.js;
+var ScriptInterpreter = bitcore.ScriptInterpreter;
 
 var sig_canonical = require('../data/bitcoind/sig_canonical');
 var sig_noncanonical = require('../data/bitcoind/sig_noncanonical');
@@ -217,13 +218,17 @@ describe('Signature', function() {
           }
           it('should be ' + (expected ? '' : 'in') + 'valid for fixture #' + i, function() {
             var sighex = vector;
-            Signature.isTxDER(new Buffer(sighex, 'hex')).should.equal(expected);
+            var interp = ScriptInterpreter();
+            interp.flags = ScriptInterpreter.SCRIPT_VERIFY_DERSIG |
+              ScriptInterpreter.SCRIPT_VERIFY_STRICTENC;
+            var result = interp.checkSignatureEncoding(new Buffer(sighex, 'hex'));
+            result.should.equal(expected);
           });
           i++;
         });
       };
       test_sigs(sig_canonical, true);
-      //test_sigs(sig_noncanonical, false);
+      test_sigs(sig_noncanonical, false);
     });
 
   });