diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 2bc83df..87f0a37 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -3647,11 +3647,11 @@ let extract_stream pdf decomp objnum =
   let data =
     match obj with
     | Pdf.Stream {contents = (_, Pdf.Got x)} -> x
-    | _ -> mkbytes 0
+    | _ -> raise (Pdf.PDFError "Stream not found")
   in
     match args.out with
     | NoOutputSpecified ->
-        ()
+        raise (Pdf.PDFError "No output specified")
     | File outname ->
         let fh = open_out_bin outname in
           output_string fh (Pdfio.string_of_bytes data);
@@ -3688,7 +3688,8 @@ let print_obj json pdf objspec =
     let obj = if objnum = 0 then pdf.Pdf.trailerdict else Pdf.lookup_obj pdf objnum in
     match Pdf.lookup_chain pdf obj chain with
     | Some x -> write x
-    | None -> ()
+    | None ->
+        Pdfe.log "Chain not found"; exit 2
   in
     match explode objspec with
     | 'P'::more ->
@@ -3709,7 +3710,10 @@ let print_version () =
 let replace_obj pdf objspec obj =
   let split_chain str = map (fun x -> "/" ^ x) (tl (String.split_on_char '/' str)) in
   let chain = split_chain objspec in
-    Pdf.replace_chain pdf chain obj
+    try
+      Pdf.replace_chain pdf chain obj
+    with
+      e -> Pdfe.log "Chain not found"; exit 2
   
 (* Call out to GhostScript to rasterize. Read back in and replace the page contents with the resultant PNG. *)
 let rasterize antialias downsample device res annots quality pdf range =
diff --git a/cpdfmanual.pdf b/cpdfmanual.pdf
index 48ed51d..3db19ea 100644
Binary files a/cpdfmanual.pdf and b/cpdfmanual.pdf differ
diff --git a/cpdfmanual.tex b/cpdfmanual.tex
index aacfc00..1502412 100644
--- a/cpdfmanual.tex
+++ b/cpdfmanual.tex
@@ -6582,7 +6582,7 @@ $ ./cpdf -obj /Root/Pages/Count cpdfmanual.pdf
 "/MCBERL+URWPalladioL-Roma"
 \end{verbatim}}
 
-\noindent To output data in JSON format instead of PDF format, use \texttt{-obj-json} in place of \texttt{-obj}.
+\noindent If the object does not exist, Cpdf will exit with code 2. To output data in JSON format instead of PDF format, use \texttt{-obj-json} in place of \texttt{-obj}.
 
 A stream may be extracted with \texttt{-extract-stream} or \texttt{-extract-stream-decompress}, which decompresses it first where possible:
 
diff --git a/cpdftweak.ml b/cpdftweak.ml
index 053be62..ce721be 100644
--- a/cpdftweak.ml
+++ b/cpdftweak.ml
@@ -263,7 +263,6 @@ let replace_dict_entry pdf key value search =
     Pdf.objselfmap (dict_entry_single_object f pdf) pdf;
     pdf.Pdf.trailerdict <- dict_entry_single_object f pdf pdf.Pdf.trailerdict
 
-(* FIXME no need to self map here, since nothing changes *)
 let print_dict_entry ~utf8 pdf key =
   let f d =
     match Pdf.lookup_direct pdf key d with