diff --git a/ClosedXML/Excel/PivotTables/PivotValues/IXLPivotValueFormat.cs b/ClosedXML/Excel/PivotTables/PivotValues/IXLPivotValueFormat.cs
index c0988d5..3c6391c 100644
--- a/ClosedXML/Excel/PivotTables/PivotValues/IXLPivotValueFormat.cs
+++ b/ClosedXML/Excel/PivotTables/PivotValues/IXLPivotValueFormat.cs
@@ -2,7 +2,7 @@
 
 namespace ClosedXML.Excel
 {
-    public interface IXLPivotValueFormat : IXLNumberFormatBase
+    public interface IXLPivotValueFormat : IXLNumberFormatBase, IEquatable<IXLNumberFormatBase>
     {
         IXLPivotValue SetNumberFormatId(Int32 value);
 
diff --git a/ClosedXML/Excel/PivotTables/PivotValues/XLPivotValueFormat.cs b/ClosedXML/Excel/PivotTables/PivotValues/XLPivotValueFormat.cs
index 819232e..7e5b918 100644
--- a/ClosedXML/Excel/PivotTables/PivotValues/XLPivotValueFormat.cs
+++ b/ClosedXML/Excel/PivotTables/PivotValues/XLPivotValueFormat.cs
@@ -79,19 +79,17 @@
         }
 
         #region Overrides
-        public bool Equals(IXLPivotValueFormat other)
+        public bool Equals(IXLNumberFormatBase other)
         {
-            var otherNf = other as XLPivotValueFormat;
-
             return
-                _numberFormatId == otherNf._numberFormatId
-                && _format == otherNf._format
+                _numberFormatId == other.NumberFormatId
+                && _format == other.Format
                 ;
         }
 
         public override bool Equals(object obj)
         {
-            return Equals((XLPivotValueFormat)obj);
+            return Equals((IXLNumberFormatBase)obj);
         }
 
         public override int GetHashCode()
diff --git a/ClosedXML/Excel/Style/IXLNumberFormat.cs b/ClosedXML/Excel/Style/IXLNumberFormat.cs
index ac12786..2a8ef5e 100644
--- a/ClosedXML/Excel/Style/IXLNumberFormat.cs
+++ b/ClosedXML/Excel/Style/IXLNumberFormat.cs
@@ -2,7 +2,7 @@
 
 namespace ClosedXML.Excel
 {
-    public interface IXLNumberFormat : IXLNumberFormatBase, IEquatable<IXLNumberFormat>
+    public interface IXLNumberFormat : IXLNumberFormatBase, IEquatable<IXLNumberFormatBase>
     {
         IXLStyle SetNumberFormatId(Int32 value);
 
diff --git a/ClosedXML/Excel/Style/XLNumberFormat.cs b/ClosedXML/Excel/Style/XLNumberFormat.cs
index 1b6620a..7a15cc7 100644
--- a/ClosedXML/Excel/Style/XLNumberFormat.cs
+++ b/ClosedXML/Excel/Style/XLNumberFormat.cs
@@ -6,13 +6,11 @@
     {
         #region IXLNumberFormat Members
 
-        public bool Equals(IXLNumberFormat other)
+        public bool Equals(IXLNumberFormatBase other)
         {
-            var otherNf = other as XLNumberFormat;
-
             return
-                _numberFormatId == otherNf._numberFormatId
-                && _format == otherNf._format
+                _numberFormatId == other.NumberFormatId
+                && _format == other.Format
                 ;
         }
 
@@ -25,7 +23,7 @@
 
         public override bool Equals(object obj)
         {
-            return Equals((XLNumberFormat)obj);
+            return Equals((IXLNumberFormatBase)obj);
         }
 
         public override int GetHashCode()
@@ -114,4 +112,4 @@
 
         #endregion
     }
-}
\ No newline at end of file
+}
diff --git a/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs b/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
index 8c5b0ce..4bd5979 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
@@ -16,6 +16,8 @@
             [DebuggerBrowsable(DebuggerBrowsableState.Never)]
             private readonly Dictionary<Int32, StyleInfo> _sharedStyles;
             [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+            private readonly Dictionary<Int32, NumberFormatInfo> _sharedNumberFormats;
+            [DebuggerBrowsable(DebuggerBrowsableState.Never)]
             private readonly Dictionary<IXLFont, FontInfo> _sharedFonts;
             [DebuggerBrowsable(DebuggerBrowsableState.Never)]
             private readonly HashSet<string> _tableNames;
@@ -27,6 +29,7 @@
             {
                 _relIdGenerator = new RelIdGenerator();
                 _sharedStyles = new Dictionary<Int32, StyleInfo>();
+                _sharedNumberFormats = new Dictionary<int, NumberFormatInfo>();
                 _sharedFonts = new Dictionary<IXLFont, FontInfo>();
                 _tableNames = new HashSet<String>();
                 _tableId = 0;
@@ -43,6 +46,11 @@
                 [DebuggerStepThrough]
                 get { return _sharedStyles; }
             }
+            public Dictionary<Int32, NumberFormatInfo> SharedNumberFormats
+            {
+                [DebuggerStepThrough]
+                get { return _sharedNumberFormats; }
+            }
             public Dictionary<IXLFont, FontInfo> SharedFonts
             {
                 [DebuggerStepThrough]
diff --git a/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/Excel/XLWorkbook_Save.cs
index 791b00c..88617f9 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -1820,7 +1820,7 @@
 
                 var pivotTablePart =
                     worksheetPart.AddNewPart<PivotTablePart>(context.RelIdGenerator.GetNext(RelType.Workbook));
-                GeneratePivotTablePartContent(pivotTablePart, pt, pivotCache.CacheId);
+                GeneratePivotTablePartContent(pivotTablePart, pt, pivotCache.CacheId, context);
 
                 pivotTablePart.AddPart(pivotTableCacheDefinitionPart, context.RelIdGenerator.GetNext(RelType.Workbook));
             }
@@ -1914,7 +1914,7 @@
         }
 
         // Generates content of pivotTablePart
-        private static void GeneratePivotTablePartContent(PivotTablePart pivotTablePart, IXLPivotTable pt, uint cacheId)
+        private static void GeneratePivotTablePartContent(PivotTablePart pivotTablePart, IXLPivotTable pt, uint cacheId, SaveContext context)
         {
             var pivotTableDefinition = new PivotTableDefinition
             {
@@ -2020,14 +2020,17 @@
                 }
             }
 
-            // -2 is the sentinal value for "Values"
-            if (pt.ColumnLabels.Any(cl => cl.SourceName == XLConstants.PivotTableValuesSentinalLabel))
-                columnFields.AppendChild(new Field { Index = -2 });
-
-            if (pt.RowLabels.Any(rl => rl.SourceName == XLConstants.PivotTableValuesSentinalLabel))
+            if (pt.Values.Count() > 1)
             {
-                pivotTableDefinition.DataOnRows = true;
-                rowFields.AppendChild(new Field { Index = -2 });
+                // -2 is the sentinal value for "Values"
+                if (pt.ColumnLabels.Any(cl => cl.SourceName == XLConstants.PivotTableValuesSentinalLabel))
+                    columnFields.AppendChild(new Field { Index = -2 });
+
+                if (pt.RowLabels.Any(rl => rl.SourceName == XLConstants.PivotTableValuesSentinalLabel))
+                {
+                    pivotTableDefinition.DataOnRows = true;
+                    rowFields.AppendChild(new Field { Index = -2 });
+                }
             }
 
             foreach (var xlpf in pt.Fields)
@@ -2174,13 +2177,19 @@
                     pt.SourceRange.Columns().FirstOrDefault(c => c.Cell(1).Value.ToString() == value.SourceName);
                 if (sourceColumn == null) continue;
 
+                UInt32 numberFormatId = 0;
+                if (value.NumberFormat.NumberFormatId != -1 || context.SharedNumberFormats.ContainsKey(value.NumberFormat.NumberFormatId))
+                    numberFormatId = (UInt32)value.NumberFormat.NumberFormatId;
+                else if (context.SharedNumberFormats.Any(snf => snf.Value.NumberFormat.Format == value.NumberFormat.Format))
+                    numberFormatId = (UInt32)context.SharedNumberFormats.First(snf => snf.Value.NumberFormat.Format == value.NumberFormat.Format).Key;
+
                 var df = new DataField
                 {
                     Name = value.CustomName,
                     Field = (UInt32)sourceColumn.ColumnNumber() - 1,
                     Subtotal = value.SummaryFormula.ToOpenXml(),
                     ShowDataAs = value.Calculation.ToOpenXml(),
-                    NumberFormatId = (UInt32)value.NumberFormat.NumberFormatId
+                    NumberFormatId = numberFormatId
                 };
 
                 if (!String.IsNullOrEmpty(value.BaseField))
@@ -2639,6 +2648,11 @@
             }
 
             var allSharedNumberFormats = ResolveNumberFormats(workbookStylesPart, sharedNumberFormats, defaultFormatId);
+            foreach (var nf in allSharedNumberFormats)
+            {
+                context.SharedNumberFormats.Add(nf.Value.NumberFormatId, nf.Value);
+            }
+
             ResolveFonts(workbookStylesPart, context);
             var allSharedFills = ResolveFills(workbookStylesPart, sharedFills);
             var allSharedBorders = ResolveBorders(workbookStylesPart, sharedBorders);