diff --git a/src/main/java/com/iqser/red/pdftronlogic/commons/OCGWatermarkRemovalService.java b/src/main/java/com/iqser/red/pdftronlogic/commons/OCGWatermarkRemovalService.java
index 85b2b59..9a655f0 100644
--- a/src/main/java/com/iqser/red/pdftronlogic/commons/OCGWatermarkRemovalService.java
+++ b/src/main/java/com/iqser/red/pdftronlogic/commons/OCGWatermarkRemovalService.java
@@ -28,10 +28,12 @@ public class OCGWatermarkRemovalService {
     @SneakyThrows
     private boolean hasOCGWatermarks(PDFDoc pdfDoc) {
         Obj ocgs = pdfDoc.getOCGs();
-        for (int i = 0; i < ocgs.size(); i++) {
-            Group group = new Group(ocgs.getAt(i));
-            if (group.isValid() && group.getName().equals("Watermark")) {
-                return true;
+        if(ocgs != null) {
+            for (int i = 0; i < ocgs.size(); i++) {
+                Group group = new Group(ocgs.getAt(i));
+                if (group.isValid() && group.getName().equals("Watermark")) {
+                    return true;
+                }
             }
         }
         return false;