diff --git a/CMakeLists.txt b/CMakeLists.txt
index 71c12c11..851824d2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -629,11 +629,11 @@ list(APPEND LIBDWARFS_COMMON_SRC
 )
 
 list(APPEND LIBDWARFS_READER_SRC
-  src/dwarfs/block_cache.cpp
   src/dwarfs/block_range.cpp
   src/dwarfs/cached_block.cpp
   src/dwarfs/filesystem_v2.cpp
   src/dwarfs/fs_section.cpp
+  src/dwarfs/internal/block_cache.cpp
   src/dwarfs/internal/inode_reader_v2.cpp
   src/dwarfs/internal/metadata_v2.cpp
   src/dwarfs/internal/metadata_types.cpp
diff --git a/include/dwarfs/block_cache.h b/include/dwarfs/internal/block_cache.h
similarity index 98%
rename from include/dwarfs/block_cache.h
rename to include/dwarfs/internal/block_cache.h
index 975a2bf2..1836c18f 100644
--- a/include/dwarfs/block_cache.h
+++ b/include/dwarfs/internal/block_cache.h
@@ -42,6 +42,8 @@ class mmif;
 class os_access;
 class performance_monitor;
 
+namespace internal {
+
 class block_cache {
  public:
   block_cache(logger& lgr, os_access const& os, std::shared_ptr<mmif> mm,
@@ -81,4 +83,6 @@ class block_cache {
  private:
   std::unique_ptr<impl> impl_;
 };
+
+} // namespace internal
 } // namespace dwarfs
diff --git a/src/dwarfs/filesystem_v2.cpp b/src/dwarfs/filesystem_v2.cpp
index fe4ac11a..abe52c92 100644
--- a/src/dwarfs/filesystem_v2.cpp
+++ b/src/dwarfs/filesystem_v2.cpp
@@ -32,7 +32,6 @@
 
 #include <fmt/format.h>
 
-#include <dwarfs/block_cache.h>
 #include <dwarfs/block_compressor.h>
 #include <dwarfs/block_data.h>
 #include <dwarfs/categorizer.h>
@@ -43,6 +42,7 @@
 #include <dwarfs/fs_section.h>
 #include <dwarfs/fstypes.h>
 #include <dwarfs/history.h>
+#include <dwarfs/internal/block_cache.h>
 #include <dwarfs/internal/inode_reader_v2.h>
 #include <dwarfs/internal/metadata_v2.h>
 #include <dwarfs/internal/worker_group.h>
@@ -610,7 +610,7 @@ filesystem_<LoggerPolicy>::filesystem_(
     PERFMON_CLS_TIMER_INIT(readv_future)
     PERFMON_CLS_TIMER_INIT(readv_future_throw) // clang-format on
 {
-  block_cache cache(lgr, os_, mm_, options.block_cache, perfmon);
+  internal::block_cache cache(lgr, os_, mm_, options.block_cache, perfmon);
   filesystem_parser parser(mm_, image_offset_);
 
   if (parser.has_index()) {
diff --git a/src/dwarfs/block_cache.cpp b/src/dwarfs/internal/block_cache.cpp
similarity index 99%
rename from src/dwarfs/block_cache.cpp
rename to src/dwarfs/internal/block_cache.cpp
index 90f177c6..941ed58a 100644
--- a/src/dwarfs/block_cache.cpp
+++ b/src/dwarfs/internal/block_cache.cpp
@@ -42,9 +42,9 @@
 #include <folly/stats/Histogram.h>
 #include <folly/system/ThreadName.h>
 
-#include <dwarfs/block_cache.h>
 #include <dwarfs/cached_block.h>
 #include <dwarfs/fs_section.h>
+#include <dwarfs/internal/block_cache.h>
 #include <dwarfs/internal/worker_group.h>
 #include <dwarfs/logger.h>
 #include <dwarfs/mmif.h>
@@ -52,7 +52,9 @@
 #include <dwarfs/performance_monitor.h>
 #include <dwarfs/util.h>
 
-namespace dwarfs {
+namespace dwarfs::internal {
+
+namespace {
 
 class sequential_access_detector {
  public:
@@ -791,6 +793,8 @@ class block_cache_ final : public block_cache::impl {
   cache_tidy_config tidy_config_;
 };
 
+} // namespace
+
 block_cache::block_cache(logger& lgr, os_access const& os,
                          std::shared_ptr<mmif> mm,
                          const block_cache_options& options,
@@ -798,4 +802,4 @@ block_cache::block_cache(logger& lgr, os_access const& os,
     : impl_(make_unique_logging_object<impl, block_cache_, logger_policies>(
           lgr, os, std::move(mm), options, std::move(perfmon))) {}
 
-} // namespace dwarfs
+} // namespace dwarfs::internal
diff --git a/src/dwarfs/internal/inode_reader_v2.cpp b/src/dwarfs/internal/inode_reader_v2.cpp
index 1285752d..91d5785a 100644
--- a/src/dwarfs/internal/inode_reader_v2.cpp
+++ b/src/dwarfs/internal/inode_reader_v2.cpp
@@ -32,8 +32,8 @@
 #include <folly/container/EvictingCacheMap.h>
 #include <folly/stats/Histogram.h>
 
-#include <dwarfs/block_cache.h>
 #include <dwarfs/fstypes.h>
+#include <dwarfs/internal/block_cache.h>
 #include <dwarfs/internal/inode_reader_v2.h>
 #include <dwarfs/internal/offset_cache.h>
 #include <dwarfs/iovec_read_buf.h>