diff --git a/OpenXmlFormats/Spreadsheet/Sheet.cs b/OpenXmlFormats/Spreadsheet/Sheet.cs
index e96aa1621..538ff99e1 100644
--- a/OpenXmlFormats/Spreadsheet/Sheet.cs
+++ b/OpenXmlFormats/Spreadsheet/Sheet.cs
@@ -2701,7 +2701,7 @@ internal void Write(StreamWriter sw, string nodeName)
             XmlHelper.WriteAttribute(sw, "r1", this.r1);
             XmlHelper.WriteAttribute(sw, "r2", this.r2);
             XmlHelper.WriteAttribute(sw, "ca", this.ca, false);
-            if(this.si!=0)
+            if(this.t == ST_CellFormulaType.shared || this.si!=0)
                 XmlHelper.WriteAttribute(sw, "si", this.si, true);
             XmlHelper.WriteAttribute(sw, "bx", this.bx, false);
             if (!string.IsNullOrEmpty(this.valueField))