diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 0893b45..6a6ffa7 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -578,49 +578,41 @@ QPDF::reserveObjects(QPDFObjectHandle foreign, ObjCopier& obj_copier, bool top)
     }
 
     if (foreign.isPagesObject()) {
-        QTC::TC("qpdf", "QPDF not copying pages object");
         return;
     }
 
     if (foreign.isIndirect()) {
         QPDFObjGen foreign_og(foreign.getObjGen());
         if (!obj_copier.visiting.add(foreign_og)) {
-            QTC::TC("qpdf", "QPDF loop reserving objects");
             return;
         }
         if (obj_copier.object_map.contains(foreign_og)) {
-            QTC::TC("qpdf", "QPDF already reserved object");
-            if (!(top && foreign.isPageObject() && obj_copier.object_map[foreign_og].isNull())) {
+            if (!(top && foreign.isPageObject() && obj_copier.object_map[foreign_og].null())) {
                 obj_copier.visiting.erase(foreign);
                 return;
             }
         } else {
-            QTC::TC("qpdf", "QPDF copy indirect");
             obj_copier.object_map[foreign_og] =
                 foreign.isStream() ? newStream() : newIndirectNull();
-            if ((!top) && foreign.isPageObject()) {
-                QTC::TC("qpdf", "QPDF not crossing page boundary");
+            if (!top && foreign.isPageObject()) {
                 obj_copier.visiting.erase(foreign_og);
                 return;
             }
         }
-        obj_copier.to_copy.push_back(foreign);
+        obj_copier.to_copy.emplace_back(foreign);
     }
 
     if (foreign_tc == ::ot_array) {
-        QTC::TC("qpdf", "QPDF reserve array");
         for (auto const& item: foreign.as_array()) {
             reserveObjects(item, obj_copier, false);
         }
     } else if (foreign_tc == ::ot_dictionary) {
-        QTC::TC("qpdf", "QPDF reserve dictionary");
         for (auto const& item: foreign.as_dictionary()) {
             if (!item.second.null()) {
                 reserveObjects(item.second, obj_copier, false);
             }
         }
     } else if (foreign_tc == ::ot_stream) {
-        QTC::TC("qpdf", "QPDF reserve stream");
         reserveObjects(foreign.getDict(), obj_copier, false);
     }
 
diff --git a/libqpdf/QPDFAcroFormDocumentHelper.cc b/libqpdf/QPDFAcroFormDocumentHelper.cc
index e3a0c95..7adbe08 100644
--- a/libqpdf/QPDFAcroFormDocumentHelper.cc
+++ b/libqpdf/QPDFAcroFormDocumentHelper.cc
@@ -487,11 +487,7 @@ QPDFAcroFormDocumentHelper::adjustInheritedFields(
         if (field.getObjectHandle().hasKey(key)) {
             return true;
         }
-        auto oh = field.getInheritableFieldValue(key);
-        if (!oh.isNull()) {
-            return true;
-        }
-        return false;
+        return !field.getInheritableFieldValue(key).null();
     };
 
     if (override_da || override_q) {
@@ -499,14 +495,12 @@ QPDFAcroFormDocumentHelper::adjustInheritedFields(
         if (override_da && (!has_explicit(cur_field, "/DA"))) {
             std::string da = cur_field.getDefaultAppearance();
             if (da != from_default_da) {
-                QTC::TC("qpdf", "QPDFAcroFormDocumentHelper override da");
                 obj.replaceKey("/DA", QPDFObjectHandle::newUnicodeString(from_default_da));
             }
         }
         if (override_q && (!has_explicit(cur_field, "/Q"))) {
             int q = cur_field.getQuadding();
             if (q != from_default_q) {
-                QTC::TC("qpdf", "QPDFAcroFormDocumentHelper override q");
                 obj.replaceKey("/Q", QPDFObjectHandle::newInteger(from_default_q));
             }
         }
@@ -675,17 +669,15 @@ QPDFAcroFormDocumentHelper::adjustAppearanceStream(
             std::string const& old_key = i2.first;
             std::string const& new_key = i2.second;
             auto existing_new = subdict.getKey(new_key);
-            if (!existing_new.isNull()) {
+            if (!existing_new.null()) {
                 // The resource dictionary already has a key in it matching what we remapped an old
                 // key to, so we'll have to move it out of the way. Stick it in merge_with, which we
                 // will re-merge with the dictionary when we're done. We know merge_with already has
                 // dictionaries for all the top keys.
-                QTC::TC("qpdf", "QPDFAcroFormDocumentHelper ap conflict");
                 merge_with.getKey(top_key).replaceKey(new_key, existing_new);
             }
             auto existing_old = subdict.getKey(old_key);
-            if (!existing_old.isNull()) {
-                QTC::TC("qpdf", "QPDFAcroFormDocumentHelper ap rename");
+            if (!existing_old.null()) {
                 subdict.replaceKey(new_key, existing_old);
                 subdict.removeKey(old_key);
             }
@@ -878,7 +870,7 @@ QPDFAcroFormDocumentHelper::transformAnnotations(
         bool have_parent = false;
         if (ffield_oh.isStream()) {
             ffield.warn("ignoring form field that's a stream");
-        } else if ((!ffield_oh.isNull()) && (!ffield_oh.isIndirect())) {
+        } else if (!ffield_oh.null() && !ffield_oh.isIndirect()) {
             ffield.warn("ignoring form field not indirect");
         } else if (!ffield.null()) {
             // A field and its associated annotation can be the same object. This matters because we
diff --git a/libqpdf/QPDFFormFieldObjectHelper.cc b/libqpdf/QPDFFormFieldObjectHelper.cc
index 59d12dc..fe9ff1c 100644
--- a/libqpdf/QPDFFormFieldObjectHelper.cc
+++ b/libqpdf/QPDFFormFieldObjectHelper.cc
@@ -25,7 +25,7 @@ QPDFFormFieldObjectHelper::QPDFFormFieldObjectHelper() :
 bool
 QPDFFormFieldObjectHelper::isNull()
 {
-    return oh().isNull();
+    return oh().null();
 }
 
 QPDFFormFieldObjectHelper
@@ -39,7 +39,7 @@ QPDFFormFieldObjectHelper::getTopLevelField(bool* is_different)
 {
     auto top_field = oh();
     QPDFObjGen::set seen;
-    while (seen.add(top_field) && !top_field.getKeyIfDict("/Parent").isNull()) {
+    while (seen.add(top_field) && !top_field.getKeyIfDict("/Parent").null()) {
         top_field = top_field.getKey("/Parent");
         if (is_different) {
             *is_different = true;
@@ -72,13 +72,12 @@ QPDFFormFieldObjectHelper::getInheritableFieldValue(std::string const& name)
         return QPDFObjectHandle::newNull();
     }
     QPDFObjectHandle result(node.getKey(name));
-    if (result.isNull()) {
+    if (result.null()) {
         QPDFObjGen::set seen;
         while (seen.add(node) && node.hasKey("/Parent")) {
             node = node.getKey("/Parent");
             result = node.getKey(name);
-            if (!result.isNull()) {
-                QTC::TC("qpdf", "QPDFFormFieldObjectHelper non-trivial inheritance");
+            if (!result.null()) {
                 return result;
             }
         }
@@ -118,10 +117,9 @@ QPDFFormFieldObjectHelper::getFullyQualifiedName()
     std::string result;
     QPDFObjectHandle node = oh();
     QPDFObjGen::set seen;
-    while (!node.isNull() && seen.add(node)) {
+    while (!node.null() && seen.add(node)) {
         if (node.getKey("/T").isString()) {
             if (!result.empty()) {
-                QTC::TC("qpdf", "QPDFFormFieldObjectHelper non-trivial qualified name");
                 result = "." + result;
             }
             result = node.getKey("/T").getUTF8Value() + result;
@@ -360,18 +358,17 @@ QPDFFormFieldObjectHelper::setRadioButtonValue(QPDFObjectHandle name)
     //   is a member, set /AS to /Off.
     // Note that we never turn on /NeedAppearances when setting a radio button field.
     QPDFObjectHandle parent = oh().getKey("/Parent");
-    if (parent.isDictionary() && parent.getKey("/Parent").isNull()) {
+    if (parent.isDictionary() && parent.getKey("/Parent").null()) {
         QPDFFormFieldObjectHelper ph(parent);
         if (ph.isRadioButton()) {
             // This is most likely one of the individual buttons. Try calling on the parent.
-            QTC::TC("qpdf", "QPDFFormFieldObjectHelper set parent radio button");
             ph.setRadioButtonValue(name);
             return;
         }
     }
 
     QPDFObjectHandle kids = oh().getKey("/Kids");
-    if (!(isRadioButton() && parent.isNull() && kids.isArray())) {
+    if (!(isRadioButton() && parent.null() && kids.isArray())) {
         warn("don't know how to set the value of this field as a radio button");
         return;
     }
@@ -384,7 +381,6 @@ QPDFFormFieldObjectHelper::setRadioButtonValue(QPDFObjectHandle name)
             for (auto const& grandkid: kid.getKey("/Kids").as_array()) {
                 AP = grandkid.getKey("/AP");
                 if (!AP.null()) {
-                    QTC::TC("qpdf", "QPDFFormFieldObjectHelper radio button grandkid");
                     annot = grandkid;
                     break;
                 }
@@ -393,16 +389,13 @@ QPDFFormFieldObjectHelper::setRadioButtonValue(QPDFObjectHandle name)
             annot = kid;
         }
         if (!annot) {
-            QTC::TC("qpdf", "QPDFObjectHandle broken radio button");
             warn("unable to set the value of this radio button");
             continue;
         }
         if (AP.isDictionary() && AP.getKey("/N").isDictionary() &&
             AP.getKey("/N").hasKey(name.getName())) {
-            QTC::TC("qpdf", "QPDFFormFieldObjectHelper turn on radio button");
             annot.replaceKey("/AS", name);
         } else {
-            QTC::TC("qpdf", "QPDFFormFieldObjectHelper turn off radio button");
             annot.replaceKey("/AS", QPDFObjectHandle::newName("/Off"));
         }
     }
@@ -749,7 +742,7 @@ void
 QPDFFormFieldObjectHelper::generateTextAppearance(QPDFAnnotationObjectHelper& aoh)
 {
     QPDFObjectHandle AS = aoh.getAppearanceStream("/N");
-    if (AS.isNull()) {
+    if (AS.null()) {
         QTC::TC("qpdf", "QPDFFormFieldObjectHelper create AS from scratch");
         QPDFObjectHandle::Rectangle rect = aoh.getRect();
         QPDFObjectHandle::Rectangle bbox(0, 0, rect.urx - rect.llx, rect.ury - rect.lly);
@@ -759,8 +752,7 @@ QPDFFormFieldObjectHelper::generateTextAppearance(QPDFAnnotationObjectHelper& ao
         AS = QPDFObjectHandle::newStream(oh().getOwningQPDF(), "/Tx BMC\nEMC\n");
         AS.replaceDict(dict);
         QPDFObjectHandle AP = aoh.getAppearanceDictionary();
-        if (AP.isNull()) {
-            QTC::TC("qpdf", "QPDFFormFieldObjectHelper create AP from scratch");
+        if (AP.null()) {
             aoh.getObjectHandle().replaceKey("/AP", QPDFObjectHandle::newDictionary());
             AP = aoh.getAppearanceDictionary();
         }
@@ -808,7 +800,6 @@ QPDFFormFieldObjectHelper::generateTextAppearance(QPDFAnnotationObjectHelper& ao
             found_font_in_dr = font.isDictionary();
         }
         if (found_font_in_dr && resources.isDictionary()) {
-            QTC::TC("qpdf", "QPDFFormFieldObjectHelper get font from /DR");
             if (resources.isIndirect()) {
                 resources = resources.getQPDF().makeIndirectObject(resources.shallowCopy());
                 AS.getDict().replaceKey("/Resources", resources);
@@ -821,7 +812,6 @@ QPDFFormFieldObjectHelper::generateTextAppearance(QPDFAnnotationObjectHelper& ao
         if (font.isDictionary() && font.getKey("/Encoding").isName()) {
             std::string encoding = font.getKey("/Encoding").getName();
             if (encoding == "/WinAnsiEncoding") {
-                QTC::TC("qpdf", "QPDFFormFieldObjectHelper WinAnsi");
                 encoder = &QUtil::utf8_to_win_ansi;
             } else if (encoding == "/MacRomanEncoding") {
                 encoder = &QUtil::utf8_to_mac_roman;
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 3748701..c9e91a1 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -464,7 +464,7 @@ QPDFJob::createQPDF()
     if (m->remove_info) {
         auto trailer = pdf.getTrailer();
         auto mod_date = trailer.getKey("/Info").getKeyIfDict("/ModDate");
-        if (mod_date.isNull()) {
+        if (mod_date.null()) {
             trailer.removeKey("/Info");
         } else {
             auto info = trailer.replaceKeyAndGetNew(
@@ -2064,7 +2064,7 @@ static void
 maybe_set_pagemode(QPDF& pdf, std::string const& pagemode)
 {
     auto root = pdf.getRoot();
-    if (root.getKey("/PageMode").isNull()) {
+    if (root.getKey("/PageMode").null()) {
         root.replaceKey("/PageMode", QPDFObjectHandle::newName(pagemode));
     }
 }
diff --git a/libqpdf/QPDFOutlineDocumentHelper.cc b/libqpdf/QPDFOutlineDocumentHelper.cc
index f1774ff..bcba309 100644
--- a/libqpdf/QPDFOutlineDocumentHelper.cc
+++ b/libqpdf/QPDFOutlineDocumentHelper.cc
@@ -1,5 +1,6 @@
 #include <qpdf/QPDFOutlineDocumentHelper.hh>
 
+#include <qpdf/QPDFObjectHandle_private.hh>
 #include <qpdf/QTC.hh>
 
 class QPDFOutlineDocumentHelper::Members
@@ -36,7 +37,7 @@ QPDFOutlineDocumentHelper::QPDFOutlineDocumentHelper(QPDF& qpdf) :
     }
     QPDFObjectHandle cur = outlines.getKey("/First");
     QPDFObjGen::set seen;
-    while (!cur.isNull() && seen.add(cur)) {
+    while (!cur.null() && seen.add(cur)) {
         m->outlines.emplace_back(QPDFOutlineObjectHelper::Accessor::create(cur, *this, 1));
         cur = cur.getKey("/Next");
     }
diff --git a/libqpdf/QPDFOutlineObjectHelper.cc b/libqpdf/QPDFOutlineObjectHelper.cc
index 640826a..4c3a2bf 100644
--- a/libqpdf/QPDFOutlineObjectHelper.cc
+++ b/libqpdf/QPDFOutlineObjectHelper.cc
@@ -1,5 +1,6 @@
 #include <qpdf/QPDFOutlineObjectHelper.hh>
 
+#include <qpdf/QPDFObjectHandle_private.hh>
 #include <qpdf/QPDFOutlineDocumentHelper.hh>
 #include <qpdf/QTC.hh>
 
@@ -19,13 +20,12 @@ QPDFOutlineObjectHelper::QPDFOutlineObjectHelper(
         return;
     }
     if (QPDFOutlineDocumentHelper::Accessor::checkSeen(m->dh, a_oh.getObjGen())) {
-        QTC::TC("qpdf", "QPDFOutlineObjectHelper loop");
         return;
     }
 
     QPDFObjGen::set children;
     QPDFObjectHandle cur = a_oh.getKey("/First");
-    while (!cur.isNull() && cur.isIndirect() && children.add(cur)) {
+    while (!cur.null() && cur.isIndirect() && children.add(cur)) {
         QPDFOutlineObjectHelper new_ooh(cur, dh, 1 + depth);
         new_ooh.m->parent = std::make_shared<QPDFOutlineObjectHelper>(*this);
         m->kids.push_back(new_ooh);
diff --git a/libqpdf/QPDFPageDocumentHelper.cc b/libqpdf/QPDFPageDocumentHelper.cc
index 3d0fbdb..154443e 100644
--- a/libqpdf/QPDFPageDocumentHelper.cc
+++ b/libqpdf/QPDFPageDocumentHelper.cc
@@ -1,6 +1,7 @@
 #include <qpdf/QPDFPageDocumentHelper.hh>
 
 #include <qpdf/QPDFAcroFormDocumentHelper.hh>
+#include <qpdf/QPDFObjectHandle_private.hh>
 #include <qpdf/QPDF_private.hh>
 #include <qpdf/QTC.hh>
 #include <qpdf/QUtil.hh>
@@ -127,7 +128,7 @@ QPDFPageDocumentHelper::flattenAnnotationsForPage(
                 ++next_fx;
             }
             new_content += content;
-        } else if (process && !aoh.getAppearanceDictionary().isNull()) {
+        } else if (process && !aoh.getAppearanceDictionary().null()) {
             // If an annotation has no selected appearance stream, just drop the annotation when
             // flattening. This can happen for unchecked checkboxes and radio buttons, popup windows
             // associated with comments that aren't visible, and other types of annotations that
diff --git a/libqpdf/QPDFPageLabelDocumentHelper.cc b/libqpdf/QPDFPageLabelDocumentHelper.cc
index 54f8238..878c54e 100644
--- a/libqpdf/QPDFPageLabelDocumentHelper.cc
+++ b/libqpdf/QPDFPageLabelDocumentHelper.cc
@@ -1,6 +1,6 @@
 #include <qpdf/QPDFPageLabelDocumentHelper.hh>
 
-#include <qpdf/QTC.hh>
+#include <qpdf/QPDFObjectHandle_private.hh>
 
 class QPDFPageLabelDocumentHelper::Members
 {
@@ -72,7 +72,7 @@ QPDFPageLabelDocumentHelper::getLabelsForPageRange(
     // prior entry. If there is no entry for the first page, fabricate one that would match how the
     // page would look in a new file in which it also didn't have an explicit label.
     QPDFObjectHandle label = getLabelForPage(start_idx);
-    if (label.isNull()) {
+    if (label.null()) {
         label = QPDFObjectHandle::newDictionary();
         label.replaceKey("/St", QPDFObjectHandle::newInteger(1 + new_start_idx));
     }
diff --git a/libqpdf/QPDFPageObjectHelper.cc b/libqpdf/QPDFPageObjectHelper.cc
index 1a0098c..530247f 100644
--- a/libqpdf/QPDFPageObjectHelper.cc
+++ b/libqpdf/QPDFPageObjectHelper.cc
@@ -238,15 +238,14 @@ QPDFPageObjectHelper::getAttribute(
     auto dict = is_form_xobject ? oh().getDict() : oh();
     auto result = dict.getKey(name);
 
-    if (!is_form_xobject && result.isNull() &&
+    if (!is_form_xobject && result.null() &&
         (name == "/MediaBox" || name == "/CropBox" || name == "/Resources" || name == "/Rotate")) {
         QPDFObjectHandle node = dict;
         QPDFObjGen::set seen{};
         while (seen.add(node) && node.hasKey("/Parent")) {
             node = node.getKey("/Parent");
             result = node.getKey(name);
-            if (!result.isNull()) {
-                QTC::TC("qpdf", "QPDFPageObjectHelper non-trivial inheritance");
+            if (!result.null()) {
                 inherited = true;
                 break;
             }
@@ -256,10 +255,9 @@ QPDFPageObjectHelper::getAttribute(
         QTC::TC("qpdf", "QPDFPageObjectHelper copy shared attribute", is_form_xobject ? 0 : 1);
         result = dict.replaceKeyAndGetNew(name, result.shallowCopy());
     }
-    if (result.isNull() && get_fallback) {
+    if (result.null() && get_fallback) {
         result = get_fallback();
-        if (copy_if_fallback && !result.isNull()) {
-            QTC::TC("qpdf", "QPDFPageObjectHelper copied fallback");
+        if (copy_if_fallback && !result.null()) {
             result = dict.replaceKeyAndGetNew(name, result.shallowCopy());
         } else {
             QTC::TC("qpdf", "QPDFPageObjectHelper used fallback without copying");
@@ -670,7 +668,7 @@ QPDFPageObjectHelper::getMatrixForTransformations(bool invert)
     }
     QPDFObjectHandle rotate_obj = getAttribute("/Rotate", false);
     QPDFObjectHandle scale_obj = getAttribute("/UserUnit", false);
-    if (!(rotate_obj.isNull() && scale_obj.isNull())) {
+    if (!(rotate_obj.null() && scale_obj.null())) {
         QPDFObjectHandle::Rectangle rect = bbox.getArrayAsRectangle();
         double width = rect.urx - rect.llx;
         double height = rect.ury - rect.lly;
@@ -724,7 +722,7 @@ QPDFPageObjectHelper::getFormXObjectForPage(bool handle_transformations)
     result.replaceStreamData(provider, QPDFObjectHandle::newNull(), QPDFObjectHandle::newNull());
     QPDFObjectHandle rotate_obj = getAttribute("/Rotate", false);
     QPDFObjectHandle scale_obj = getAttribute("/UserUnit", false);
-    if (handle_transformations && (!(rotate_obj.isNull() && scale_obj.isNull()))) {
+    if (handle_transformations && !(rotate_obj.null() && scale_obj.null())) {
         newdict.replaceKey("/Matrix", QPDFObjectHandle::newArray(getMatrixForTransformations()));
     }
 
@@ -963,8 +961,7 @@ QPDFPageObjectHelper::flattenRotation(QPDFAcroFormDocumentHelper* afdh)
     oh().addPageContents(qpdf.newStream("\nQ\n"), false);
     oh().removeKey("/Rotate");
     QPDFObjectHandle rotate_obj = getAttribute("/Rotate", false);
-    if (!rotate_obj.isNull()) {
-        QTC::TC("qpdf", "QPDFPageObjectHelper flatten inherit rotate");
+    if (!rotate_obj.null()) {
         oh().replaceKey("/Rotate", QPDFObjectHandle::newInteger(0));
     }
 
diff --git a/libqpdf/QPDFStreamFilter.cc b/libqpdf/QPDFStreamFilter.cc
index 66a2f76..a4949de 100644
--- a/libqpdf/QPDFStreamFilter.cc
+++ b/libqpdf/QPDFStreamFilter.cc
@@ -1,9 +1,11 @@
 #include <qpdf/QPDFStreamFilter.hh>
 
+#include <qpdf/QPDFObjectHandle_private.hh>
+
 bool
 QPDFStreamFilter::setDecodeParms(QPDFObjectHandle decode_parms)
 {
-    return decode_parms.isNull();
+    return decode_parms.null();
 }
 
 bool
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 66f0dd0..3ac9942 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -1782,12 +1782,11 @@ QPDFWriter::writeObjectStream(QPDFObjectHandle object)
         write(" /Filter /FlateDecode");
     }
     write(" /N ").write(offsets.size()).write_qdf("\n ").write(" /First ").write(first);
-    if (!object.isNull()) {
+    if (!object.null()) {
         // If the original object has an /Extends key, preserve it.
         QPDFObjectHandle dict = object.getDict();
         QPDFObjectHandle extends = dict.getKey("/Extends");
         if (extends.isIndirect()) {
-            QTC::TC("qpdf", "QPDFWriter copy Extends");
             write_qdf("\n ").write(" /Extends ");
             unparseChild(extends, 1, f_in_ostream);
         }
diff --git a/libqpdf/QPDF_Dictionary.cc b/libqpdf/QPDF_Dictionary.cc
index f02a7bb..f606b2b 100644
--- a/libqpdf/QPDF_Dictionary.cc
+++ b/libqpdf/QPDF_Dictionary.cc
@@ -40,7 +40,7 @@ BaseDictionary::getKeys()
 {
     std::set<std::string> result;
     for (auto& iter: dict()->items) {
-        if (!iter.second.isNull()) {
+        if (!iter.second.null()) {
             result.insert(iter.first);
         }
     }
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index 992cc84..73a9b38 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -376,7 +376,7 @@ Stream::filterable(
 
     auto filter_obj = s->stream_dict.getKey("/Filter");
 
-    if (filter_obj.isNull()) {
+    if (filter_obj.null()) {
         // No filters
         return true;
     }
diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc
index e5dca43..8be325a 100644
--- a/libqpdf/QPDF_encryption.cc
+++ b/libqpdf/QPDF_encryption.cc
@@ -681,7 +681,7 @@ QPDF::EncryptionParameters::initialize(QPDF& qpdf)
           (encryption_dict.getKey("/Filter").getName() == "/Standard"))) {
         throw unsupported("unsupported encryption filter");
     }
-    if (!encryption_dict.getKey("/SubFilter").isNull()) {
+    if (!encryption_dict.getKey("/SubFilter").null()) {
         qpdf.warn(unsupported("file uses encryption SubFilters, which qpdf does not support"));
     }
 
diff --git a/libqpdf/QPDF_linearization.cc b/libqpdf/QPDF_linearization.cc
index 8ac8e51..bcce0e6 100644
--- a/libqpdf/QPDF_linearization.cc
+++ b/libqpdf/QPDF_linearization.cc
@@ -167,7 +167,7 @@ QPDF::readLinearizationData()
     QPDFObjectHandle P = m->lindict.getKey("/P");
 
     if (!(H.isArray() && O.isInteger() && E.isInteger() && N.isInteger() && T.isInteger() &&
-          (P.isInteger() || P.isNull()))) {
+          (P.isInteger() || P.null()))) {
         throw damagedPDF(
             "linearization dictionary",
             "some keys in linearization dictionary are of the wrong type");
@@ -577,7 +577,7 @@ QPDF::getUncompressedObject(QPDFObjectHandle& oh, QPDFWriter::ObjTable const& ob
 {
     if (obj.contains(oh)) {
         if (auto id = obj[oh].object_stream; id > 0) {
-            return oh.isNull() ? oh : getObject(id, 0);
+            return oh.null() ? oh : getObject(id, 0);
         }
     }
     return oh;
@@ -1284,7 +1284,7 @@ QPDF::calculateLinearizationData(T const& object_stream_data)
         thumb = getUncompressedObject(thumb, object_stream_data);
         QPDFObjGen thumb_og(thumb.getObjGen());
         // Output the thumbnail itself
-        if (lc_thumbnail_private.erase(thumb_og) && !thumb.isNull()) {
+        if (lc_thumbnail_private.erase(thumb_og) && !thumb.null()) {
             m->part9.emplace_back(thumb);
         } else {
             // No internal error this time...there's nothing to stop this object from having
@@ -1394,7 +1394,7 @@ QPDF::pushOutlinesToPart(
 {
     QPDFObjectHandle root = getRoot();
     QPDFObjectHandle outlines = root.getKey("/Outlines");
-    if (outlines.isNull()) {
+    if (outlines.null()) {
         return;
     }
     outlines = getUncompressedObject(outlines, object_stream_data);
diff --git a/libqpdf/QPDF_objects.cc b/libqpdf/QPDF_objects.cc
index aa65e0d..354af00 100644
--- a/libqpdf/QPDF_objects.cc
+++ b/libqpdf/QPDF_objects.cc
@@ -910,8 +910,7 @@ QPDF::processXRefIndex(
         }
         QTC::TC("qpdf", "QPDF xref /Index is array", index_vec.size() == 2 ? 0 : 1);
         return {num_entries, indx};
-    } else if (Index_obj.isNull()) {
-        QTC::TC("qpdf", "QPDF xref /Index is null");
+    } else if (Index_obj.null()) {
         return {size, {{0, size}}};
     } else {
         throw damaged("Cross-reference stream does not have a proper /Index key");
@@ -1256,11 +1255,9 @@ QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
         auto length_obj = object.getKey("/Length");
 
         if (!length_obj.isInteger()) {
-            if (length_obj.isNull()) {
-                QTC::TC("qpdf", "QPDF stream without length");
+            if (length_obj.null()) {
                 throw damagedPDF(offset, "stream dictionary lacks /Length key");
             }
-            QTC::TC("qpdf", "QPDF stream length not integer");
             throw damagedPDF(offset, "/Length key in stream dictionary is not an integer");
         }
 
@@ -1269,7 +1266,6 @@ QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
         m->file->seek(stream_offset, SEEK_SET);
         m->file->seek(toO(length), SEEK_CUR);
         if (!readToken(*m->file).isWord("endstream")) {
-            QTC::TC("qpdf", "QPDF missing endstream");
             throw damagedPDF("expected endstream");
         }
     } catch (QPDFExc& e) {
diff --git a/libqpdf/SF_FlateLzwDecode.cc b/libqpdf/SF_FlateLzwDecode.cc
index bd5454d..e71cb24 100644
--- a/libqpdf/SF_FlateLzwDecode.cc
+++ b/libqpdf/SF_FlateLzwDecode.cc
@@ -5,12 +5,13 @@
 #include <qpdf/Pl_PNGFilter.hh>
 #include <qpdf/Pl_TIFFPredictor.hh>
 #include <qpdf/QIntC.hh>
+#include <qpdf/QPDFObjectHandle_private.hh>
 #include <qpdf/QTC.hh>
 
 bool
 SF_FlateLzwDecode::setDecodeParms(QPDFObjectHandle decode_parms)
 {
-    if (decode_parms.isNull()) {
+    if (decode_parms.null()) {
         return true;
     }
 
diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index a4136fb..2fee084 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -64,9 +64,6 @@ QPDFParser bad brace 0
 QPDFParser bad brace in parseRemainder 0
 QPDFParser bad array close 0
 QPDFParser bad array close in parseRemainder 0
-QPDF stream without length 0
-QPDF stream length not integer 0
-QPDF missing endstream 0
 QPDFParser bad dictionary close 0
 QPDFParser bad dictionary close in parseRemainder 0
 QPDF can't find xref 0
@@ -87,9 +84,7 @@ QPDF found xref stream 0
 QPDF ignoring XRefStm in trailer 0
 QPDF xref deleted object 0
 SF_FlateLzwDecode PNG filter 0
-QPDF xref /Index is null 0
 QPDF xref /Index is array 1
-QPDFWriter copy Extends 0
 QPDFWriter encrypt object stream 0
 QPDFWriter uncompressing page dictionary 0
 QPDFWriter uncompressing root 0
@@ -204,18 +199,11 @@ QPDF_Stream unknown stream length 0
 QPDF replaceReserved 0
 QPDF copyForeign direct 0
 QPDF copyForeign not foreign 0
-QPDF copy indirect 0
-QPDF loop reserving objects 0
 QPDF replace indirect 0
 QPDF replace array 0
 QPDF replace dictionary 0
 QPDF replace stream 0
-QPDF reserve array 0
-QPDF reserve dictionary 0
-QPDF reserve stream 0
-QPDF not crossing page boundary 0
 QPDF replace foreign indirect with null 0
-QPDF not copying pages object 0
 QPDF insert foreign page 0
 QPDFWriter foreign object 0
 QPDFWriter copy use_aes 1
@@ -249,7 +237,6 @@ QPDF_optimization indirect outlines 0
 QPDF xref space 2
 QPDFJob pages range omitted in middle 0
 QPDFJob npages 0
-QPDF already reserved object 0
 QPDFWriter standard deterministic ID 1
 QPDFWriter linearized deterministic ID 1
 qpdf-c called qpdf_set_deterministic_ID 0
@@ -312,8 +299,6 @@ QPDFObjectHandle erase array bounds 0
 qpdf-c called qpdf_check_pdf 0
 QPDF xref loop 0
 QPDFParser too deep 0
-QPDFFormFieldObjectHelper non-trivial inheritance 0
-QPDFFormFieldObjectHelper non-trivial qualified name 0
 QPDFFormFieldObjectHelper TU present 0
 QPDFFormFieldObjectHelper TM present 0
 QPDFFormFieldObjectHelper TU absent 0
@@ -340,7 +325,6 @@ QPDFOutlineObjectHelper direct dest 0
 QPDFOutlineObjectHelper action dest 0
 QPDFOutlineObjectHelper named dest 0
 QPDFOutlineDocumentHelper string named dest 0
-QPDFOutlineObjectHelper loop 0
 QPDFObjectHandle merge top type mismatch 0
 QPDFObjectHandle merge shallow copy 0
 QPDFObjectHandle merge array 0
@@ -361,12 +345,7 @@ QPDFObjectHandle replace with copy 0
 QPDFPageDocumentHelper indirect as resources 0
 QPDFAnnotationObjectHelper forbidden flags 0
 QPDFAnnotationObjectHelper missing required flags 0
-QPDFFormFieldObjectHelper set parent radio button 0
-QPDFFormFieldObjectHelper radio button grandkid 0
-QPDFFormFieldObjectHelper turn on radio button 0
-QPDFFormFieldObjectHelper turn off radio button 0
 QPDFFormFieldObjectHelper checkbox kid widget 0
-QPDFObjectHandle broken radio button 0
 QPDFFormFieldObjectHelper set checkbox AS 0
 QPDFObjectHandle broken checkbox 0
 QPDFFormFieldObjectHelper list not found 0
@@ -376,7 +355,6 @@ QPDFFormFieldObjectHelper list last too high 0
 QPDFJob image optimize no pipeline 0
 QPDFJob image optimize no shrink 0
 QPDFJob image optimize too small 0
-QPDFFormFieldObjectHelper WinAnsi 0
 QPDF pipe foreign encrypted stream 0
 QPDF copy foreign stream with provider 0
 QPDF copy foreign stream with buffer 0
@@ -393,10 +371,8 @@ QPDFJob invalid utf-8 in auto 0
 QPDFJob input password hex-bytes 0
 QPDFPageDocumentHelper ignore annotation with no appearance 0
 QPDFFormFieldObjectHelper create AS from scratch 0
-QPDFFormFieldObjectHelper create AP from scratch 0
 QPDFFormFieldObjectHelper replaced BMC at EOF 0
 QPDFFormFieldObjectHelper fallback Tf 0
-QPDFPageObjectHelper non-trivial inheritance 0
 QPDFPageObjectHelper copy shared attribute 1
 QPDFJob from_nr from repeat_nr 0
 QPDF resolve duplicated page object 0
@@ -513,19 +489,13 @@ QPDFPageObjectHelper unresolved names 0
 QPDFPageObjectHelper resolving unresolved 0
 QPDFFileSpecObjectHelper empty compat_name 0
 QPDFFileSpecObjectHelper non-empty compat_name 0
-QPDFPageObjectHelper flatten inherit rotate 0
 QPDFAcroFormDocumentHelper copy annotation 3
 QPDFAcroFormDocumentHelper field with parent 3
 QPDFAcroFormDocumentHelper modify ap matrix 0
 QPDFJob pages keeping field from original 0
 QPDFObjectHandle merge reuse 0
 QPDFObjectHandle merge generate 0
-QPDFFormFieldObjectHelper get font from /DR 0
-QPDFAcroFormDocumentHelper override da 0
-QPDFAcroFormDocumentHelper override q 0
 QPDFAcroFormDocumentHelper replaced DA token 0
-QPDFAcroFormDocumentHelper ap conflict 0
-QPDFAcroFormDocumentHelper ap rename 0
 QPDFAcroFormDocumentHelper /DA parse error 0
 QPDFAcroFormDocumentHelper AP parse error 1
 QPDFJob copy fields not this file 0
@@ -614,7 +584,6 @@ QPDF_json missing json version 0
 QPDF_json bad json version 0
 QPDF_json bad calledgetallpages 0
 QPDF_json bad pushedinheritedpageresources 0
-QPDFPageObjectHelper copied fallback 0
 QPDFPageObjectHelper used fallback without copying 0
 QPDF skipping cache for known unchecked object 0
 QPDF fix dangling triggered xref reconstruction 0