1 files changed, 1 insertions, 1 deletions
diff --git a/decoder/ff_lm.h b/decoder/ff_lm.h
index 45fc1da7..10a3e9a3 100644
--- a/decoder/ff_lm.h
+++ b/decoder/ff_lm.h
@@ -26,7 +26,7 @@ class LanguageModel : public FeatureFunction {
                                      SparseVector<double>* estimated_features,
                                      void* out_context) const;
  private:
-  const int fid_;
+  int fid_; // conceptually const; mutable only to simplify constructor
   mutable LanguageModelImpl* pimpl_;
 };