diff --git a/moses/TranslationModel/CompactPT/LexicalReorderingTableCreator.cpp b/moses/TranslationModel/CompactPT/LexicalReorderingTableCreator.cpp
index 5eace2063..9fe9eec30 100644
--- a/moses/TranslationModel/CompactPT/LexicalReorderingTableCreator.cpp
+++ b/moses/TranslationModel/CompactPT/LexicalReorderingTableCreator.cpp
@@ -258,8 +258,10 @@ void LexicalReorderingTableCreator::FlushEncodedQueue(bool force)
   if(force) {
     m_lastFlushedLine = -1;
 
-    m_hash.AddRange(m_lastRange);
-    m_lastRange.clear();
+    if(!m_lastRange.empty()) {
+      m_hash.AddRange(m_lastRange);
+      m_lastRange.clear();
+    }
 
 #ifdef WITH_THREADS
     m_hash.WaitAll();
@@ -377,7 +379,6 @@ void EncodingTaskReordering::operator()()
                             encodedLine, i);
       result.push_back(packedItem);
     }
-    lines.clear();
 
     {
 #ifdef WITH_THREADS
@@ -388,6 +389,7 @@ void EncodingTaskReordering::operator()()
       m_creator.FlushEncodedQueue();
     }
 
+    lines.clear();
     result.clear();
     lines.reserve(max_lines);
     result.reserve(max_lines);
diff --git a/moses/TranslationModel/CompactPT/PhraseTableCreator.cpp b/moses/TranslationModel/CompactPT/PhraseTableCreator.cpp
index 6de3340d1..ba1dfc578 100644
--- a/moses/TranslationModel/CompactPT/PhraseTableCreator.cpp
+++ b/moses/TranslationModel/CompactPT/PhraseTableCreator.cpp
@@ -878,8 +878,10 @@ void PhraseTableCreator::FlushRankedQueue(bool force)
   }
 
   if(force) {
-    m_rnkHash.AddRange(m_lastSourceRange);
-    m_lastSourceRange.clear();
+    if(!m_lastSourceRange.empty()) {
+      m_rnkHash.AddRange(m_lastSourceRange);
+      m_lastSourceRange.clear();
+    }
 
 #ifdef WITH_THREADS
     m_rnkHash.WaitAll();
@@ -963,8 +965,10 @@ void PhraseTableCreator::FlushEncodedQueue(bool force)
       m_lastCollection.clear();
     }
 
-    m_srcHash.AddRange(m_lastSourceRange);
-    m_lastSourceRange.clear();
+    if(!m_lastSourceRange.empty()) {
+      m_srcHash.AddRange(m_lastSourceRange);
+      m_lastSourceRange.clear();
+    }
 
 #ifdef WITH_THREADS
     m_srcHash.WaitAll();