diff --git a/native_client/deepspeech.cc b/native_client/deepspeech.cc
index 96989e04..b5b0f163 100644
--- a/native_client/deepspeech.cc
+++ b/native_client/deepspeech.cc
@@ -333,11 +333,12 @@ int
 DS_EnableExternalScorer(ModelState* aCtx,
                         const char* aScorerPath)
 {
-  aCtx->scorer_.reset(new Scorer());
-  int err = aCtx->scorer_->init(aScorerPath, aCtx->alphabet_);
+  std::unique_ptr<Scorer> scorer(new Scorer());
+  int err = scorer->init(aScorerPath, aCtx->alphabet_);
   if (err != 0) {
     return DS_ERR_INVALID_SCORER;
   }
+  aCtx->scorer_ = std::move(scorer);
   return DS_ERR_OK;
 }
 
diff --git a/native_client/javascript/index.js b/native_client/javascript/index.js
index 8fd8659c..7d742aad 100644
--- a/native_client/javascript/index.js
+++ b/native_client/javascript/index.js
@@ -35,7 +35,7 @@ function Model(aModelPath) {
     const status = rets[0];
     const impl = rets[1];
     if (status !== 0) {
-        throw "CreateModel failed "+binding.ErrorCodeToErrorMessage(status)+" 0x" + status.toString(16);
+        throw "CreateModel failed with '"+binding.ErrorCodeToErrorMessage(status)+"' (0x" + status.toString(16) + ")";
     }
 
     this._impl = impl;
@@ -76,10 +76,13 @@ Model.prototype.sampleRate = function() {
  *
  * @param {string} aScorerPath The path to the external scorer file.
  *
- * @return {number} Zero on success, non-zero on failure (invalid arguments).
+ * @throws on error
  */
 Model.prototype.enableExternalScorer = function(aScorerPath) {
-    return binding.EnableExternalScorer(this._impl, aScorerPath);
+    const status = binding.EnableExternalScorer(this._impl, aScorerPath);
+    if (status !== 0) {
+        throw "EnableExternalScorer failed with '"+binding.ErrorCodeToErrorMessage(status)+"' (0x" + status.toString(16) + ")";
+    }
 }
 
 /**
@@ -139,7 +142,7 @@ Model.prototype.createStream = function() {
     const status = rets[0];
     const ctx = rets[1];
     if (status !== 0) {
-        throw "CreateStream failed "+binding.ErrorCodeToErrorMessage(status)+" 0x" + status.toString(16);
+        throw "CreateStream failed with '"+binding.ErrorCodeToErrorMessage(status)+"' (0x" + status.toString(16) + ")";
     }
     return new Stream(ctx);
 }
diff --git a/native_client/python/__init__.py b/native_client/python/__init__.py
index a6af56f1..8dec3f0c 100644
--- a/native_client/python/__init__.py
+++ b/native_client/python/__init__.py
@@ -81,10 +81,11 @@ class Model(object):
         :param scorer_path: The path to the external scorer file.
         :type scorer_path: str
 
-        :return: Zero on success, non-zero on failure.
-        :type: int
+        :throws: RuntimeError on error
         """
-        return deepspeech.impl.EnableExternalScorer(self._impl, scorer_path)
+        status = deepspeech.impl.EnableExternalScorer(self._impl, scorer_path)
+        if status != 0:
+            raise RuntimeError("EnableExternalScorer failed with '{}' (0x{:X})".format(deepspeech.impl.ErrorCodeToErrorMessage(status),status))
 
     def disableExternalScorer(self):
         """