diff --git a/src/java/org/apache/poi/hssf/dev/BiffViewer.java b/src/java/org/apache/poi/hssf/dev/BiffViewer.java
index 58753048c..3afd25a4a 100644
--- a/src/java/org/apache/poi/hssf/dev/BiffViewer.java
+++ b/src/java/org/apache/poi/hssf/dev/BiffViewer.java
@@ -179,6 +179,8 @@ public final class BiffViewer {
             case CFHeaderRecord.sid:          return new CFHeaderRecord(in);
             case CFHeader12Record.sid:        return new CFHeader12Record(in);
             case CFRuleRecord.sid:            return new CFRuleRecord(in);
+            case CFRule12Record.sid:          return new CFRule12Record(in);
+            // TODO Add CF Ex, and remove from UnknownRecord 
             case CalcCountRecord.sid:         return new CalcCountRecord(in);
             case CalcModeRecord.sid:          return new CalcModeRecord(in);
             case CategorySeriesAxisRecord.sid:return new CategorySeriesAxisRecord(in);
diff --git a/src/java/org/apache/poi/hssf/record/CFRuleBase.java b/src/java/org/apache/poi/hssf/record/CFRuleBase.java
index b7db3a7a0..449594414 100644
--- a/src/java/org/apache/poi/hssf/record/CFRuleBase.java
+++ b/src/java/org/apache/poi/hssf/record/CFRuleBase.java
@@ -347,7 +347,7 @@ public abstract class CFRuleBase extends StandardRecord {
     }
     
     protected int getFormattingBlockSize() {
-        return
+        return 6 +
           (containsFontFormattingBlock()?_fontFormatting.getRawRecord().length:0)+
           (containsBorderFormattingBlock()?8:0)+
           (containsPatternFormattingBlock()?4:0);
diff --git a/src/java/org/apache/poi/hssf/record/CFRuleRecord.java b/src/java/org/apache/poi/hssf/record/CFRuleRecord.java
index a00fde731..52678c0fd 100644
--- a/src/java/org/apache/poi/hssf/record/CFRuleRecord.java
+++ b/src/java/org/apache/poi/hssf/record/CFRuleRecord.java
@@ -114,7 +114,7 @@ public final class CFRuleRecord extends CFRuleBase {
     }
 
     protected int getDataSize() {
-        return 12 + getFormattingBlockSize() +
+        return 6 + getFormattingBlockSize() +
                getFormulaSize(getFormula1())+
                getFormulaSize(getFormula2());
     }
diff --git a/src/java/org/apache/poi/hssf/record/RecordFactory.java b/src/java/org/apache/poi/hssf/record/RecordFactory.java
index 6163fc000..c1a0f5707 100644
--- a/src/java/org/apache/poi/hssf/record/RecordFactory.java
+++ b/src/java/org/apache/poi/hssf/record/RecordFactory.java
@@ -151,6 +151,7 @@ public final class RecordFactory {
         CFHeaderRecord.class,
         CFHeader12Record.class,
         CFRuleRecord.class,
+        CFRule12Record.class,
         ChartRecord.class,
         ChartTitleFormatRecord.class,
         CodepageRecord.class,
diff --git a/src/testcases/org/apache/poi/hssf/record/TestCFRuleRecord.java b/src/testcases/org/apache/poi/hssf/record/TestCFRuleRecord.java
index e562f52f4..3be13558b 100644
--- a/src/testcases/org/apache/poi/hssf/record/TestCFRuleRecord.java
+++ b/src/testcases/org/apache/poi/hssf/record/TestCFRuleRecord.java
@@ -402,8 +402,7 @@ public final class TestCFRuleRecord extends TestCase {
         assertArrayEquals(serializedRecord, serializedClone);
     }
     
-    // TODO Fix this test!
-    public void IGNORED_testBug57231_rewrite() {
+    public void testBug57231_rewrite() {
         HSSFWorkbook wb = HSSFITestDataProvider.instance.openSampleWorkbook("57231_MixedGasReport.xls");
         assertEquals(7, wb.getNumberOfSheets());
         wb = HSSFITestDataProvider.instance.writeOutAndReadBack(wb);