diff --git a/src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java b/src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java
index 551ff75474..b866c61bf3 100644
--- a/src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java
+++ b/src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java
@@ -91,7 +91,7 @@ public final class AnalysisToolPak implements UDFFinder {
         r(m, "DEC2BIN", null);
         r(m, "DEC2HEX", null);
         r(m, "DEC2OCT", null);
-        r(m, "DELTA", null);
+        r(m, "DELTA", Delta.instance);
         r(m, "DISC", null);
         r(m, "DOLLARDE", null);
         r(m, "DOLLARFR", null);
diff --git a/src/java/org/apache/poi/ss/formula/functions/Delta.java b/src/java/org/apache/poi/ss/formula/functions/Delta.java
index 8488189aa5..2f1bd88dfc 100644
--- a/src/java/org/apache/poi/ss/formula/functions/Delta.java
+++ b/src/java/org/apache/poi/ss/formula/functions/Delta.java
@@ -17,6 +17,7 @@
 
 package org.apache.poi.ss.formula.functions;
 
+import org.apache.poi.ss.formula.OperationEvaluationContext;
 import org.apache.poi.ss.formula.eval.*;
 
 import java.math.BigDecimal;
@@ -37,7 +38,9 @@ import java.math.BigDecimal;
  *
  * @author cedric dot walter @ gmail dot com
  */
-public final class Delta extends Fixed2ArgFunction {
+public final class Delta extends Fixed2ArgFunction implements FreeRefFunction {
+
+    public static final FreeRefFunction instance = new Delta();
 
     private final static NumberEval ONE = new NumberEval(1);
     private final static NumberEval ZERO = new NumberEval(0);
@@ -72,4 +75,11 @@ public final class Delta extends Fixed2ArgFunction {
         return result == 0 ? ONE : ZERO;
     }
 
+    public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
+         if (args.length == 2) {
+            return evaluate(ec.getRowIndex(), ec.getColumnIndex(), args[0], args[1]);
+        }
+
+        return ErrorEval.VALUE_INVALID;
+    }
 }
\ No newline at end of file
diff --git a/src/testcases/org/apache/poi/ss/formula/functions/TestDeltaFunctionsFromSpreadsheet.java b/src/testcases/org/apache/poi/ss/formula/functions/TestDeltaFunctionsFromSpreadsheet.java
new file mode 100644
index 0000000000..47bea2134a
--- /dev/null
+++ b/src/testcases/org/apache/poi/ss/formula/functions/TestDeltaFunctionsFromSpreadsheet.java
@@ -0,0 +1,13 @@
+package org.apache.poi.ss.formula.functions;
+
+/**
+* Tests DELTA() as loaded from a test data spreadsheet.<p/>
+*
+* @author cedric dot walter @ gmail dot com
+*/
+public class TestDeltaFunctionsFromSpreadsheet extends BaseTestFunctionsFromSpreadsheet {
+
+    protected String getFilename() {
+        return "DeltaFunctionTestCaseData.xls";
+    }
+}
diff --git a/test-data/spreadsheet/DeltaFunctionTestCaseData.xls b/test-data/spreadsheet/DeltaFunctionTestCaseData.xls
new file mode 100644
index 0000000000..e66e96cc69
Binary files /dev/null and b/test-data/spreadsheet/DeltaFunctionTestCaseData.xls differ