diff --git a/rag/app/manual.py b/rag/app/manual.py
index 272f7148f..3fcd7b72f 100644
--- a/rag/app/manual.py
+++ b/rag/app/manual.py
@@ -229,13 +229,14 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
 
             txt, layoutno, poss = section
             if isinstance(poss, str):
-                poss = pdf_parser.extract_positions(poss)
-                first = poss[0]          # tuple: ([pn], x1, x2, y1, y2)
-                pn = first[0]           
-
-                if isinstance(pn, list):
-                    pn = pn[0]           # [pn] -> pn
-                    poss[0] = (pn, *first[1:])
+                if poss:
+                    poss = pdf_parser.extract_positions(poss)
+                    first = poss[0]          # tuple: ([pn], x1, x2, y1, y2)
+                    pn = first[0]           
+    
+                    if isinstance(pn, list) and pn:
+                        pn = pn[0]           # [pn] -> pn
+                        poss[0] = (pn, *first[1:])
 
             return (txt, layoutno, poss)
 
@@ -345,4 +346,4 @@ if __name__ == "__main__":
         pass
 
 
-    chunk(sys.argv[1], callback=dummy)
\ No newline at end of file
+    chunk(sys.argv[1], callback=dummy)