diff --git a/moses/SearchNormalBatch.h b/moses/SearchNormalBatch.h
index 7f6764635..a889d29d6 100644
--- a/moses/SearchNormalBatch.h
+++ b/moses/SearchNormalBatch.h
@@ -23,7 +23,7 @@ protected:
   std::map<int, LanguageModel*> m_dlm_ffs;
   std::map<int, StatefulFeatureFunction*> m_stateful_ffs;
   std::vector<Hypothesis*> m_partial_hypos;
-  int m_batch_size;
+  uint32_t m_batch_size;
   int m_max_stack_size;
 
   // functions for creating hypotheses