diff --git a/src/java/org/apache/poi/ss/formula/functions/Sumif.java b/src/java/org/apache/poi/ss/formula/functions/Sumif.java
index ef381adb0..977647fd2 100644
--- a/src/java/org/apache/poi/ss/formula/functions/Sumif.java
+++ b/src/java/org/apache/poi/ss/formula/functions/Sumif.java
@@ -69,6 +69,12 @@ public final class Sumif extends Var2or3ArgFunction {
 			AreaEval aeSum) {
 		// TODO - junit to prove last arg must be srcColumnIndex and not srcRowIndex
 		I_MatchPredicate mp = Countif.createCriteriaPredicate(arg1, srcRowIndex, srcColumnIndex);
+		
+		// handle empty cells
+		if(mp == null) {
+		    return NumberEval.ZERO;
+		}
+
 		double result = sumMatchingCells(aeRange, mp, aeSum);
 		return new NumberEval(result);
 	}
diff --git a/src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestXSSFBugs.java b/src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestXSSFBugs.java
index 3dd7b0f26..646fe8e5b 100644
--- a/src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestXSSFBugs.java
+++ b/src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestXSSFBugs.java
@@ -1538,7 +1538,6 @@ public final class TestXSSFBugs extends BaseTestBugzillaIssues {
      * SUMIF was throwing a NPE on some formulas
      */
     @Test
-    @Ignore("This bug is still to be fixed")
     public void testBug56420SumIfNPE() throws Exception {
         XSSFWorkbook wb = XSSFTestDataSamples.openSampleWorkbook("56420.xlsx");
         
@@ -1548,7 +1547,8 @@ public final class TestXSSFBugs extends BaseTestBugzillaIssues {
         Row r = sheet.getRow(2);
         Cell c = r.getCell(2);
         assertEquals("SUMIF($A$1:$A$4,A3,$B$1:$B$4)", c.getCellFormula());
-        evaluator.evaluateInCell(c);
+        Cell eval = evaluator.evaluateInCell(c);
+        assertEquals(0.0, eval.getNumericCellValue(), 0.0001);
     }
 
     private void bug53798Work(Workbook wb, File xlsOutput) throws IOException {
diff --git a/src/testcases/org/apache/poi/ss/formula/functions/TestSumif.java b/src/testcases/org/apache/poi/ss/formula/functions/TestSumif.java
index 6cee5eab7..c761d22f1 100644
--- a/src/testcases/org/apache/poi/ss/formula/functions/TestSumif.java
+++ b/src/testcases/org/apache/poi/ss/formula/functions/TestSumif.java
@@ -21,6 +21,8 @@ import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
 
 import org.apache.poi.ss.formula.eval.AreaEval;
+import org.apache.poi.ss.formula.eval.BlankEval;
+import org.apache.poi.ss.formula.eval.ErrorEval;
 import org.apache.poi.ss.formula.eval.NumberEval;
 import org.apache.poi.ss.formula.eval.NumericValueEval;
 import org.apache.poi.ss.formula.eval.StringEval;
@@ -107,4 +109,11 @@ public final class TestSumif extends TestCase {
 
 		confirmDouble(60, ve);
 	}
+
+	public void testEvaluateException() {
+	    assertEquals(ErrorEval.VALUE_INVALID, invokeSumif(-1, -1, BlankEval.instance, new NumberEval(30.0)));
+        assertEquals(ErrorEval.VALUE_INVALID, invokeSumif(-1, -1, BlankEval.instance, new NumberEval(30.0), new NumberEval(30.0)));
+        assertEquals(ErrorEval.VALUE_INVALID, invokeSumif(-1, -1, new NumberEval(30.0), BlankEval.instance, new NumberEval(30.0)));
+        assertEquals(ErrorEval.VALUE_INVALID, invokeSumif(-1, -1, new NumberEval(30.0), new NumberEval(30.0), BlankEval.instance));
+	}
 }