diff --git a/src/ooxml/java/org/apache/poi/xssf/streaming/SheetDataWriter.java b/src/ooxml/java/org/apache/poi/xssf/streaming/SheetDataWriter.java
index fbcb6b103d..70bdef842e 100644
--- a/src/ooxml/java/org/apache/poi/xssf/streaming/SheetDataWriter.java
+++ b/src/ooxml/java/org/apache/poi/xssf/streaming/SheetDataWriter.java
@@ -171,7 +171,7 @@ public class SheetDataWriter {
             _out.write(" hidden=\"" + (row.getHidden() ? "1" : "0") + "\"");
         }
         if(row.getCollapsed() != null) {
-        	_out.write(" collapsed=\"" + (row.getCollapsed() ? "1" : "0") + "\"");
+            _out.write(" collapsed=\"" + (row.getCollapsed() ? "1" : "0") + "\"");
         }
         
         _out.write(">\n");