diff --git a/src/java/org/apache/poi/ss/formula/CollaboratingWorkbooksEnvironment.java b/src/java/org/apache/poi/ss/formula/CollaboratingWorkbooksEnvironment.java
index f2d936f3d..58ce3d929 100644
--- a/src/java/org/apache/poi/ss/formula/CollaboratingWorkbooksEnvironment.java
+++ b/src/java/org/apache/poi/ss/formula/CollaboratingWorkbooksEnvironment.java
@@ -117,7 +117,7 @@ public final class CollaboratingWorkbooksEnvironment {
         unhookOldEnvironments(evaluators);
         hookNewEnvironment(evaluators, this);
         _unhooked = false;
-        _evaluators = evaluators;
+        _evaluators = evaluators.clone();
         _evaluatorsByName = evaluatorsByName;
     }
 
diff --git a/src/java/org/apache/poi/ss/formula/Formula.java b/src/java/org/apache/poi/ss/formula/Formula.java
index 48c7f391b..9f4f25e90 100644
--- a/src/java/org/apache/poi/ss/formula/Formula.java
+++ b/src/java/org/apache/poi/ss/formula/Formula.java
@@ -42,7 +42,7 @@ public class Formula {
 	private final int _encodedTokenLen;
 
 	private Formula(byte[] byteEncoding, int encodedTokenLen) {
-		_byteEncoding = byteEncoding;
+		_byteEncoding = byteEncoding.clone();
 		_encodedTokenLen = encodedTokenLen;
 //		if (false) { // set to true to eagerly check Ptg decoding
 //			LittleEndianByteArrayInputStream in = new LittleEndianByteArrayInputStream(byteEncoding);
diff --git a/src/java/org/apache/poi/ss/formula/FormulaCellCacheEntry.java b/src/java/org/apache/poi/ss/formula/FormulaCellCacheEntry.java
index 2d399494a..056195618 100644
--- a/src/java/org/apache/poi/ss/formula/FormulaCellCacheEntry.java
+++ b/src/java/org/apache/poi/ss/formula/FormulaCellCacheEntry.java
@@ -27,8 +27,6 @@ import org.apache.poi.ss.formula.FormulaUsedBlankCellSet.BookSheetKey;
 
 /**
  * Stores the cached result of a formula evaluation, along with the set of sensitive input cells
- * 
- * @author Josh Micich
  */
 final class FormulaCellCacheEntry extends CellCacheEntry {
 	
@@ -57,8 +55,13 @@ final class FormulaCellCacheEntry extends CellCacheEntry {
 	public void setSensitiveInputCells(CellCacheEntry[] sensitiveInputCells) {
 		// need to tell all cells that were previously used, but no longer are, 
 		// that they are not consumed by this cell any more
-		changeConsumingCells(sensitiveInputCells == null ? CellCacheEntry.EMPTY_ARRAY : sensitiveInputCells);
-		_sensitiveInputCells = sensitiveInputCells;
+	    if (sensitiveInputCells == null) {
+            _sensitiveInputCells = null;
+	        changeConsumingCells(CellCacheEntry.EMPTY_ARRAY);
+	    } else {
+	        _sensitiveInputCells = sensitiveInputCells.clone();
+	        changeConsumingCells(_sensitiveInputCells);
+	    }
 	}
 
 	public void clearFormulaEntry() {
diff --git a/src/java/org/apache/poi/ss/formula/ParseNode.java b/src/java/org/apache/poi/ss/formula/ParseNode.java
index a671ede59..a41ec2634 100644
--- a/src/java/org/apache/poi/ss/formula/ParseNode.java
+++ b/src/java/org/apache/poi/ss/formula/ParseNode.java
@@ -28,8 +28,6 @@ import org.apache.poi.ss.formula.function.FunctionMetadataRegistry;
  * Represents a syntactic element from a formula by encapsulating the corresponding <tt>Ptg</tt>
  * token.  Each <tt>ParseNode</tt> may have child <tt>ParseNode</tt>s in the case when the wrapped
  * <tt>Ptg</tt> is non-atomic.
- *
- * @author Josh Micich
  */
 final class ParseNode {
 
@@ -44,7 +42,7 @@ final class ParseNode {
 			throw new IllegalArgumentException("token must not be null");
 		}
 		_token = token;
-		_children = children;
+		_children = children.clone();
 		_isIf = isIf(token);
 		int tokenCount = 1;
 		for (int i = 0; i < children.length; i++) {