diff --git a/core/src/main/java/com/yahoo/oak/EntryHashSet.java b/core/src/main/java/com/yahoo/oak/EntryHashSet.java
index dc9b2fab..c3f76c91 100644
--- a/core/src/main/java/com/yahoo/oak/EntryHashSet.java
+++ b/core/src/main/java/com/yahoo/oak/EntryHashSet.java
@@ -207,8 +207,8 @@ private boolean isKeyAndEntryKeyEqual(KeyBuffer tempKeyBuff, K key, int idx, int
     ** --> ctx.key, ctx.value, ctx.keyHash keep the data of the entry's key, value, and key hash
      */
     private EntryState getEntryState(ThreadContext ctx, int idx, K key, int keyHash) {
-        boolean keyReadResult = false;
-        boolean valueReadResult = false;
+        boolean keyReadResult;
+        boolean valueReadResult;
 
         // optimization, as invalid key reference should be the most frequent case
         if (getKeyReference(idx) == config.keysMemoryManager.getInvalidReference()) {
@@ -675,14 +675,12 @@ boolean isEntryDeleted(ValueBuffer tempValue, int ei) {
         return tempValue.getSlice().isDeleted() != ValueUtils.ValueResult.FALSE;
     }
 
-    /**
-     * identify the next non zero entry
-     * @param currentIndex index of the current entry
-     * @return
-     */
     @Override
     int getNextNonZeroIndex(int currentIndex) {
-        int nxtIdx = mapOfCleanEntries.nextSetBit(currentIndex + 1);
+        int nxtIdx;
+        synchronized (mapOfCleanEntries) {
+            nxtIdx = mapOfCleanEntries.nextSetBit(currentIndex + 1);
+        }
         if (nxtIdx == -1) {
             nxtIdx = INVALID_ENTRY_INDEX;
         }
diff --git a/core/src/main/java/com/yahoo/oak/HashChunk.java b/core/src/main/java/com/yahoo/oak/HashChunk.java
index 32fe5fc0..aa3e0ad6 100644
--- a/core/src/main/java/com/yahoo/oak/HashChunk.java
+++ b/core/src/main/java/com/yahoo/oak/HashChunk.java
@@ -333,7 +333,7 @@ class HashChunkIter implements BasicChunkIter {
 
 
         /**
-         * find the index of the next occupied entry in the entryies array
+         * find the index of the first occupied entry in the entries array
          * @param ctx
          * @return index of the next occupied entry, or INVALID_ENTRY_INDEX if no such index exists
          */