diff --git a/include/dwarfs/writer/categorizer.h b/include/dwarfs/writer/categorizer.h
index a3927ea6..cc430c66 100644
--- a/include/dwarfs/writer/categorizer.h
+++ b/include/dwarfs/writer/categorizer.h
@@ -43,6 +43,7 @@ class variables_map;
 
 namespace dwarfs {
 
+class file_access;
 class logger;
 
 namespace writer {
@@ -224,8 +225,8 @@ class categorizer_info {
 class categorizer_factory : public categorizer_info {
  public:
   virtual std::unique_ptr<categorizer>
-  create(logger& lgr,
-         boost::program_options::variables_map const& vm) const = 0;
+  create(logger& lgr, boost::program_options::variables_map const& vm,
+         std::shared_ptr<file_access const> const& fa) const = 0;
 };
 
 class categorizer_registry {
@@ -234,7 +235,8 @@ class categorizer_registry {
 
   std::unique_ptr<categorizer>
   create(logger& lgr, std::string const& name,
-         boost::program_options::variables_map const& vm) const;
+         boost::program_options::variables_map const& vm,
+         std::shared_ptr<file_access const> const& fa) const;
 
   void add_options(boost::program_options::options_description& opts) const;
 
diff --git a/src/writer/categorizer.cpp b/src/writer/categorizer.cpp
index 8352bb85..e5e40ddc 100644
--- a/src/writer/categorizer.cpp
+++ b/src/writer/categorizer.cpp
@@ -400,16 +400,16 @@ void categorizer_registry::register_factory(
   }
 }
 
-std::unique_ptr<categorizer>
-categorizer_registry::create(logger& lgr, std::string const& name,
-                             po::variables_map const& vm) const {
+std::unique_ptr<categorizer> categorizer_registry::create(
+    logger& lgr, std::string const& name, po::variables_map const& vm,
+    std::shared_ptr<file_access const> const& fa) const {
   auto it = factories_.find(name);
 
   if (it == factories_.end()) {
     DWARFS_THROW(runtime_error, "unknown categorizer: " + name);
   }
 
-  return it->second->create(lgr, vm);
+  return it->second->create(lgr, vm, fa);
 }
 
 void categorizer_registry::add_options(po::options_description& opts) const {
diff --git a/src/writer/categorizer/fits_categorizer.cpp b/src/writer/categorizer/fits_categorizer.cpp
index db6a5ffa..332e2b75 100644
--- a/src/writer/categorizer/fits_categorizer.cpp
+++ b/src/writer/categorizer/fits_categorizer.cpp
@@ -454,7 +454,8 @@ class fits_categorizer_factory : public categorizer_factory {
   }
 
   std::unique_ptr<categorizer>
-  create(logger& lgr, po::variables_map const& /*vm*/) const override {
+  create(logger& lgr, po::variables_map const& /*vm*/,
+         std::shared_ptr<file_access const> const& /*fa*/) const override {
     return make_unique_logging_object<categorizer, fits_categorizer_,
                                       logger_policies>(lgr);
   }
diff --git a/src/writer/categorizer/hotness_categorizer.cpp b/src/writer/categorizer/hotness_categorizer.cpp
index d0817773..3cd162aa 100644
--- a/src/writer/categorizer/hotness_categorizer.cpp
+++ b/src/writer/categorizer/hotness_categorizer.cpp
@@ -23,7 +23,6 @@
 #include <atomic>
 #include <cassert>
 #include <cstring>
-#include <fstream>
 #include <numeric>
 #include <unordered_set>
 #include <vector>
@@ -33,6 +32,7 @@
 #include <fmt/format.h>
 
 #include <dwarfs/error.h>
+#include <dwarfs/file_access.h>
 #include <dwarfs/logger.h>
 #include <dwarfs/util.h>
 #include <dwarfs/writer/categorizer.h>
@@ -52,7 +52,8 @@ struct hotness_categorizer_config {
 template <typename LoggerPolicy>
 class hotness_categorizer_ final : public random_access_categorizer {
  public:
-  hotness_categorizer_(logger& lgr, hotness_categorizer_config const& cfg);
+  hotness_categorizer_(logger& lgr, hotness_categorizer_config const& cfg,
+                       std::shared_ptr<file_access const> const& fa);
 
   std::span<std::string_view const> categories() const override;
 
@@ -72,20 +73,23 @@ class hotness_categorizer_ final : public random_access_categorizer {
 
 template <typename LoggerPolicy>
 hotness_categorizer_<LoggerPolicy>::hotness_categorizer_(
-    logger& lgr, hotness_categorizer_config const& cfg)
+    logger& lgr, hotness_categorizer_config const& cfg,
+    std::shared_ptr<file_access const> const& fa)
     : LOG_PROXY_INIT(lgr)
     , cfg_{cfg} {
   auto const& file = cfg_.hotness_list;
 
   if (!file.empty()) {
-    std::ifstream ifs{file};
-    if (!ifs) {
-      DWARFS_THROW(runtime_error,
-                   fmt::format("failed to open file '{}'", file));
+    std::error_code ec;
+    auto input = fa->open_input(file, ec);
+
+    if (ec) {
+      DWARFS_THROW(runtime_error, fmt::format("failed to open file '{}': {}",
+                                              file, ec.message()));
     }
 
     std::string line;
-    while (std::getline(ifs, line)) {
+    while (std::getline(input->is(), line)) {
       auto const path = std::filesystem::path{line}.relative_path();
       LOG_DEBUG << "hotness categorizer: adding path '" << path << "'";
       if (!hotness_set_.emplace(path.string()).second) {
@@ -118,7 +122,8 @@ inode_fragments hotness_categorizer_<LoggerPolicy>::categorize(
   if (!hotness_set_.empty()) {
     auto const rel_path = path.relative_path();
 
-    LOG_DEBUG << "hotness categorizer: checking path '" << rel_path << "'";
+    LOG_DEBUG << "hotness categorizer: checking path '" << rel_path << "' ('"
+              << path.full_path() << "')";
 
     if (auto it = hotness_set_.find(rel_path.string());
         it != hotness_set_.end()) {
@@ -163,9 +168,10 @@ class hotness_categorizer_factory : public categorizer_factory {
   }
 
   std::unique_ptr<categorizer>
-  create(logger& lgr, po::variables_map const& /*vm*/) const override {
+  create(logger& lgr, po::variables_map const& /*vm*/,
+         std::shared_ptr<file_access const> const& fa) const override {
     return make_unique_logging_object<categorizer, hotness_categorizer_,
-                                      logger_policies>(lgr, cfg_);
+                                      logger_policies>(lgr, cfg_, fa);
   }
 
  private:
diff --git a/src/writer/categorizer/incompressible_categorizer.cpp b/src/writer/categorizer/incompressible_categorizer.cpp
index 2ff7a410..b3d65472 100644
--- a/src/writer/categorizer/incompressible_categorizer.cpp
+++ b/src/writer/categorizer/incompressible_categorizer.cpp
@@ -291,7 +291,8 @@ class incompressible_categorizer_factory : public categorizer_factory {
   }
 
   std::unique_ptr<categorizer>
-  create(logger& lgr, po::variables_map const& /*vm*/) const override {
+  create(logger& lgr, po::variables_map const& /*vm*/,
+         std::shared_ptr<file_access const> const& /*fa*/) const override {
     auto cfg = cfg_;
     cfg.min_input_size = parse_size_with_unit(min_input_size_str_);
     cfg.block_size = parse_size_with_unit(block_size_str_);
diff --git a/src/writer/categorizer/pcmaudio_categorizer.cpp b/src/writer/categorizer/pcmaudio_categorizer.cpp
index 687814dc..caeb3fc0 100644
--- a/src/writer/categorizer/pcmaudio_categorizer.cpp
+++ b/src/writer/categorizer/pcmaudio_categorizer.cpp
@@ -1168,7 +1168,8 @@ class pcmaudio_categorizer_factory : public categorizer_factory {
   }
 
   std::unique_ptr<categorizer>
-  create(logger& lgr, po::variables_map const& /*vm*/) const override {
+  create(logger& lgr, po::variables_map const& /*vm*/,
+         std::shared_ptr<file_access const> const& /*fa*/) const override {
     return make_unique_logging_object<categorizer, pcmaudio_categorizer_,
                                       logger_policies>(lgr);
   }
diff --git a/test/fits_categorizer_test.cpp b/test/fits_categorizer_test.cpp
index 52aace7f..2a0e30d4 100644
--- a/test/fits_categorizer_test.cpp
+++ b/test/fits_categorizer_test.cpp
@@ -70,7 +70,7 @@ class fits_categorizer_fixture : public Base {
 
     catmgr = std::make_shared<writer::categorizer_manager>(lgr, "/");
 
-    catmgr->add(catreg.create(lgr, "fits", vm));
+    catmgr->add(catreg.create(lgr, "fits", vm, nullptr));
   }
 
  public:
diff --git a/test/incompressible_categorizer_test.cpp b/test/incompressible_categorizer_test.cpp
index 42fdbb32..bfb682d6 100644
--- a/test/incompressible_categorizer_test.cpp
+++ b/test/incompressible_categorizer_test.cpp
@@ -94,7 +94,7 @@ class incompressible_categorizer_fixture : public Base {
 
     catmgr = std::make_shared<writer::categorizer_manager>(lgr, "/");
 
-    catmgr->add(catreg.create(lgr, "incompressible", vm));
+    catmgr->add(catreg.create(lgr, "incompressible", vm, nullptr));
   }
 
   // void TearDown() override {
diff --git a/test/pcmaudio_categorizer_test.cpp b/test/pcmaudio_categorizer_test.cpp
index 9f078888..d89a7055 100644
--- a/test/pcmaudio_categorizer_test.cpp
+++ b/test/pcmaudio_categorizer_test.cpp
@@ -217,7 +217,7 @@ TEST(pcmaudio_categorizer, requirements) {
   auto& catreg = writer::categorizer_registry::instance();
   auto catmgr = writer::categorizer_manager(logger, "/");
 
-  catmgr.add(catreg.create(logger, "pcmaudio", vm));
+  catmgr.add(catreg.create(logger, "pcmaudio", vm, nullptr));
 
   try {
     catmgr.set_metadata_requirements(
@@ -307,7 +307,7 @@ class pcmaudio_error_test : public testing::Test {
   void SetUp() override {
     boost::program_options::variables_map vm;
     auto& catreg = writer::categorizer_registry::instance();
-    catmgr.add(catreg.create(logger, "pcmaudio", vm));
+    catmgr.add(catreg.create(logger, "pcmaudio", vm, nullptr));
 
     catmgr.set_metadata_requirements(
         catmgr.category_value("pcmaudio/waveform").value(),
diff --git a/tools/src/mkdwarfs_main.cpp b/tools/src/mkdwarfs_main.cpp
index 725b5caf..7ac8ea4e 100644
--- a/tools/src/mkdwarfs_main.cpp
+++ b/tools/src/mkdwarfs_main.cpp
@@ -762,7 +762,7 @@ int mkdwarfs_main(int argc, sys_char** argv, iolayer const& iol) {
 
     for (auto const& name : catreg.categorizer_names()) {
       stream_logger lgr(iol.term, iol.err);
-      auto categorizer = catreg.create(lgr, name, vm);
+      auto categorizer = catreg.create(lgr, name, vm, iol.file);
       iol.out << "  [" << name << "]\n";
       for (auto cat : categorizer->categories()) {
         iol.out << "    " << cat << "\n";
@@ -1187,7 +1187,8 @@ int mkdwarfs_main(int argc, sys_char** argv, iolayer const& iol) {
         std::make_shared<writer::categorizer_manager>(lgr, path);
 
     for (auto const& name : categorizers) {
-      options.inode.categorizer_mgr->add(catreg.create(lgr, name, vm));
+      options.inode.categorizer_mgr->add(
+          catreg.create(lgr, name, vm, iol.file));
     }
   }