diff --git a/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/internal/NoCloseInputStream.java b/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/internal/NoCloseInputStream.java
index 38cd6d593f..b27685aab2 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/internal/NoCloseInputStream.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/internal/NoCloseInputStream.java
@@ -17,9 +17,12 @@
 
 package org.apache.poi.openxml4j.opc.internal;
 
+import org.apache.poi.util.Internal;
+
 import java.io.FilterInputStream;
 import java.io.InputStream;
 
+@Internal
 final class NoCloseInputStream extends FilterInputStream {
     NoCloseInputStream(InputStream stream) {
         super(stream);