diff --git a/poi-examples/src/main/java/org/apache/poi/examples/xssf/eventusermodel/FromHowTo.java b/poi-examples/src/main/java/org/apache/poi/examples/xssf/eventusermodel/FromHowTo.java
index 14d5fbd9e8..fbe4f58822 100644
--- a/poi-examples/src/main/java/org/apache/poi/examples/xssf/eventusermodel/FromHowTo.java
+++ b/poi-examples/src/main/java/org/apache/poi/examples/xssf/eventusermodel/FromHowTo.java
@@ -136,7 +136,7 @@ public class FromHowTo {
             if(nextIsString && StringUtil.isNotBlank(lastContents)) {
                 Integer idx = Integer.valueOf(lastContents);
                 lastContents = lruCache.get(idx);
-                if (lastContents == null && !lruCache.containsKey(idx)) {
+                if (lastContents == null && !lruCache.containsKey(idx) && sst != null) {
                     lastContents = sst.getItemAt(idx).getString();
                     lruCache.put(idx, lastContents);
                 }
diff --git a/test-data/spreadsheet/clusterfuzz-testcase-minimized-POIXSSFFuzzer-5089447305609216.xlsx b/test-data/spreadsheet/clusterfuzz-testcase-minimized-POIXSSFFuzzer-5089447305609216.xlsx
new file mode 100644
index 0000000000..7b30e5ca9d
Binary files /dev/null and b/test-data/spreadsheet/clusterfuzz-testcase-minimized-POIXSSFFuzzer-5089447305609216.xlsx differ
diff --git a/test-data/spreadsheet/stress.xls b/test-data/spreadsheet/stress.xls
index 1e6d98a3a8..f32cb34e16 100644
Binary files a/test-data/spreadsheet/stress.xls and b/test-data/spreadsheet/stress.xls differ