diff --git a/poi/src/main/java/org/apache/poi/ddf/UnknownEscherRecord.java b/poi/src/main/java/org/apache/poi/ddf/UnknownEscherRecord.java
index 67b6bc6317..98434aaace 100644
--- a/poi/src/main/java/org/apache/poi/ddf/UnknownEscherRecord.java
+++ b/poi/src/main/java/org/apache/poi/ddf/UnknownEscherRecord.java
@@ -103,7 +103,7 @@ public final class UnknownEscherRecord extends EscherRecord {
                 bytesWritten += childBytesWritten;
                 offset += childBytesWritten;
                 bytesRemaining -= childBytesWritten;
-                getChildRecords().add( child );
+                addChildRecord( child );
             }
             return bytesWritten;
         }
diff --git a/test-data/publisher/clusterfuzz-testcase-minimized-POIHPBFFuzzer-4918886059278336.pub b/test-data/publisher/clusterfuzz-testcase-minimized-POIHPBFFuzzer-4918886059278336.pub
new file mode 100644
index 0000000000..c901951b19
Binary files /dev/null and b/test-data/publisher/clusterfuzz-testcase-minimized-POIHPBFFuzzer-4918886059278336.pub differ
diff --git a/test-data/spreadsheet/stress.xls b/test-data/spreadsheet/stress.xls
index 94775397c8..4b0be32353 100644
Binary files a/test-data/spreadsheet/stress.xls and b/test-data/spreadsheet/stress.xls differ