diff --git a/src/calibre/utils/podofo/doc.cpp b/src/calibre/utils/podofo/doc.cpp
index ed91b02cd7..0134b28d02 100644
--- a/src/calibre/utils/podofo/doc.cpp
+++ b/src/calibre/utils/podofo/doc.cpp
@@ -130,9 +130,9 @@ PDFDoc_save_to_fileobj(PDFDoc *self, PyObject *args) {
 
 static PyObject *
 PDFDoc_uncompress_pdf(PDFDoc *self, PyObject *args) {
-    for (TIVecObjects it = self->doc->GetObjects().begin(); it != self->doc->GetObjects().end(); it++) {
-        if((*it)->HasStream()) {
-            PdfMemStream* stream = dynamic_cast<PdfMemStream*>((*it)->GetStream());
+    for (auto &it : self->doc->GetObjects()) {
+        if(it->HasStream()) {
+            PdfMemStream* stream = dynamic_cast<PdfMemStream*>(it->GetStream());
             stream->Uncompress();
         }
     }
@@ -175,16 +175,13 @@ PDFDoc_image_count(PDFDoc *self, PyObject *args) {
     const PdfObject* obj_type = NULL;
     const PdfObject* obj_sub_type = NULL;
     try {
-        TCIVecObjects it = self->doc->GetObjects().begin();
-         while( it != self->doc->GetObjects().end() ) {
-             if( (*it)->IsDictionary() ) {
-                 obj_type = (*it)->GetDictionary().GetKey( PdfName::KeyType );
-                 obj_sub_type = (*it)->GetDictionary().GetKey( PdfName::KeySubtype );
+         for (auto &it : self->doc->GetObjects()) {
+             if( it->IsDictionary() ) {
+                 obj_type = it->GetDictionary().GetKey( PdfName::KeyType );
+                 obj_sub_type = it->GetDictionary().GetKey( PdfName::KeySubtype );
                  if( ( obj_type && obj_type->IsName() && ( obj_type->GetName().GetName() == "XObject" ) ) ||
                         ( obj_sub_type && obj_sub_type->IsName() && ( obj_sub_type->GetName().GetName() == "Image" ) ) ) count++;
-                 self->doc->FreeObjectMemory( *it );
              }
-             it++;
          }
     } catch(const PdfError & err) {
         podofo_set_exception(err);
diff --git a/src/calibre/utils/podofo/fonts.cpp b/src/calibre/utils/podofo/fonts.cpp
index 0454bcc20b..e5657fed6f 100644
--- a/src/calibre/utils/podofo/fonts.cpp
+++ b/src/calibre/utils/podofo/fonts.cpp
@@ -170,15 +170,15 @@ list_fonts(PDFDoc *self, PyObject *args) {
     pyunique_ptr ans(PyList_New(0));
     if (!ans) return NULL;
     const PdfVecObjects &objects = self->doc->GetObjects();
-    for (TCIVecObjects it = objects.begin(); it != objects.end(); it++) {
-        if ((*it)->IsDictionary()) {
-            const PdfDictionary &dict = (*it)->GetDictionary();
+    for (auto &it : objects) {
+        if (it->IsDictionary()) {
+            const PdfDictionary &dict = it->GetDictionary();
             if (dictionary_has_key_name(dict, PdfName::KeyType, "Font") && dict.HasKey("BaseFont")) {
                 const std::string &name = dict.GetKey("BaseFont")->GetName().GetName();
                 const std::string &subtype = dict.GetKey(PdfName::KeySubtype)->GetName().GetName();
-                const PdfReference &ref = (*it)->Reference();
+                const PdfReference &ref = it->Reference();
                 unsigned long num = ref.ObjectNumber(), generation = ref.GenerationNumber();
-                const PdfObject *descriptor = (*it)->GetIndirectKey("FontDescriptor");
+                const PdfObject *descriptor = it->GetIndirectKey("FontDescriptor");
                 pyunique_ptr descendant_font, stream_ref, encoding, w, w2;
                 PyBytesOutputStream stream_data, to_unicode;
                 if (dict.HasKey("W")) {