diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 21dc41e..ccebf63 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -3006,7 +3006,7 @@ let collate (names, pdfs, ranges) =
     split3 (rev !nis)
 
 let warn_prerotate range pdf =
-  if not (Cpdfpage.allupright range pdf) then
+  if not args.prerotate && not (Cpdfpage.allupright range pdf) then
     Printf.eprintf "Some pages in the range have non-zero rotation or non (0,0)-based mediabox. \
                     Consider adding -prerotate or pre-processing with -upright. \
                     To silence this warning use -no-warn-rotate\n%!"
@@ -3684,6 +3684,7 @@ let go () =
             | StandardFont f -> Some f
             | OtherFont f -> None (* it's in fontname *)
           in
+            warn_prerotate range pdf;
             let pdf =
               if args.prerotate then prerotate range pdf else pdf
             and filename =
@@ -3757,8 +3758,16 @@ let go () =
             in
               write_pdf false pdf
   | Some (CombinePages over) ->
-      write_pdf false
-        (Cpdfpage.combine_pages args.fast (get_single_pdf args.op false) (pdfread_pdf_of_file None None over) false false true)
+      let underpdf = get_single_pdf args.op false in
+      let overpdf = pdfread_pdf_of_file None None over in
+        warn_prerotate (parse_pagespec underpdf "all") underpdf;
+        warn_prerotate (parse_pagespec overpdf "all") overpdf;
+        write_pdf false
+          (Cpdfpage.combine_pages
+             args.fast
+               (prerotate (parse_pagespec underpdf "all") underpdf)
+               (prerotate (parse_pagespec overpdf "all") overpdf)
+               false false true)
   | Some Encrypt ->
       let pdf = get_single_pdf args.op false in
         let pdf = Cpdfsqueeze.recompress_pdf pdf
diff --git a/cpdfpage.ml b/cpdfpage.ml
index 37379c2..1eaff82 100644
--- a/cpdfpage.ml
+++ b/cpdfpage.ml
@@ -131,21 +131,6 @@ let change_boxes f pdf page =
                  make_mediabox (f (Pdf.parse_rectangle page.Pdfpage.mediabox));
                Pdfpage.rest = rest'}
 
-(* Change a page's media box so its minimum x and y are 0, making other
-operations simpler to think about. Any shift that is done is reflected in
-other boxes (clip etc.) *)
-let rectify_boxes ?(fast=false) pdf page =
-  let minx, miny, _, _ =
-    Pdf.parse_rectangle page.Pdfpage.mediabox
-  in
-    let f (iminx, iminy, imaxx, imaxy) =
-      iminx -. minx, iminy -. miny, imaxx -. minx, imaxy -. miny
-    in
-      let page = change_boxes f pdf page in
-        if minx <> 0. || miny <> 0.
-          then
-            begin let p, _, _ = shift_page ~fast [(-.minx),(-.miny)] pdf 1 page in p end
-          else page
 
 (* Scale contents *)
 let scale_page_contents ?(fast=false) scale position pdf pnum page =
@@ -277,6 +262,22 @@ let transform_contents ?(fast=false) tr pdf page =
       Cpdfutil.transform_annotations pdf tr page.Pdfpage.rest;
       Pdfpage.prepend_operators pdf [transform_op] ~fast page
 
+(* Change a page's media box so its minimum x and y are 0, making other
+operations simpler to think about. Any shift that is done is reflected in
+other boxes (clip etc.) *)
+let rectify_boxes ?(fast=false) pdf page =
+  let minx, miny, _, _ =
+    Pdf.parse_rectangle page.Pdfpage.mediabox
+  in
+    let f (iminx, iminy, imaxx, imaxy) =
+      iminx -. minx, iminy -. miny, imaxx -. minx, imaxy -. miny
+    in
+      let page = change_boxes f pdf page in
+        if minx <> 0. || miny <> 0.
+          then
+            begin let p, _, _ = shift_page ~fast [(-.minx),(-.miny)] pdf 1 page in p end
+          else page
+
 let upright ?(fast=false) range pdf =
   if allupright range pdf then pdf else
     let upright_page _ pnum page =