diff --git a/src/integrationtest/org/apache/poi/TestAllFiles.java b/src/integrationtest/org/apache/poi/TestAllFiles.java
index af30e69efd..9ebe79d768 100644
--- a/src/integrationtest/org/apache/poi/TestAllFiles.java
+++ b/src/integrationtest/org/apache/poi/TestAllFiles.java
@@ -177,10 +177,10 @@ public class TestAllFiles {
         HANDLERS.put("spreadsheet/test_properties1", new NullFileHandler());
     }
 
-    private static final Set<String> unmodifiableHashSet(String... a) {
+    private static Set<String> unmodifiableHashSet(String... a) {
         return Collections.unmodifiableSet(hashSet(a));
     }
-    private static final Set<String> hashSet(String... a) {
+    private static Set<String> hashSet(String... a) {
         return new HashSet<String>(Arrays.asList(a));
     }
 
@@ -279,12 +279,10 @@ public class TestAllFiles {
         // sheet cloning errors
         "spreadsheet/47813.xlsx",
         "spreadsheet/56450.xls",
-        "spreadsheet/57231_MixedGasReport.xls",
         "spreadsheet/OddStyleRecord.xls",
         "spreadsheet/WithChartSheet.xlsx",
         "spreadsheet/chart_sheet.xlsx",
-        "spreadsheet/SimpleScatterChart.xlsx",
-        "spreadsheet/ConditionalFormattingSamples.xls"
+        "spreadsheet/SimpleScatterChart.xlsx"
     );
 
     private static final Set<String> IGNORED = unmodifiableHashSet(
diff --git a/src/java/org/apache/poi/hssf/record/CFRule12Record.java b/src/java/org/apache/poi/hssf/record/CFRule12Record.java
index d9d9793e9b..b10c19a99e 100644
--- a/src/java/org/apache/poi/hssf/record/CFRule12Record.java
+++ b/src/java/org/apache/poi/hssf/record/CFRule12Record.java
@@ -461,10 +461,12 @@ public final class CFRule12Record extends CFRuleBase implements FutureRecord, Cl
         rec.futureHeader.setAssociatedRange(futureHeader.getAssociatedRange().copy());
         
         super.copyTo(rec);
-        
-        rec.ext_formatting_length = ext_formatting_length;
+
+        // use min() to gracefully handle cases where the length-property and the array-lenght do not match
+        // we saw some such files in circulation
+        rec.ext_formatting_length = Math.min(ext_formatting_length, ext_formatting_data.length);
         rec.ext_formatting_data = new byte[ext_formatting_length];
-        System.arraycopy(ext_formatting_data, 0, rec.ext_formatting_data, 0, ext_formatting_length);
+        System.arraycopy(ext_formatting_data, 0, rec.ext_formatting_data, 0, rec.ext_formatting_length);
         
         rec.formula_scale = formula_scale.copy();