diff --git a/src/opustags.h b/src/opustags.h
index 93c323b..320aa23 100644
--- a/src/opustags.h
+++ b/src/opustags.h
@@ -119,13 +119,16 @@ using byte_string_view = std::basic_string_view<uint8_t>;
  * \{
  */
 
+/** fclose wrapper for std::unique_ptr’s deleter. */
+void close_file(FILE*);
+
 /**
  * Smart auto-closing FILE* handle.
  *
  * It implictly converts from an already opened FILE*.
  */
-struct file : std::unique_ptr<FILE, decltype(&fclose)> {
-	file(FILE* f = nullptr) : std::unique_ptr<FILE, decltype(&fclose)>(f, &fclose) {}
+struct file : std::unique_ptr<FILE, decltype(&close_file)> {
+	file(FILE* f = nullptr) : std::unique_ptr<FILE, decltype(&close_file)>(f, &close_file) {}
 };
 
 /**
diff --git a/src/system.cc b/src/system.cc
index a93acd3..b04cb9e 100644
--- a/src/system.cc
+++ b/src/system.cc
@@ -29,6 +29,11 @@ ot::byte_string_view operator""_bsv(const char* data, size_t size)
 	return ot::byte_string_view(reinterpret_cast<const uint8_t*>(data), size);
 }
 
+void ot::close_file(FILE* file)
+{
+	fclose(file);
+}
+
 void ot::partial_file::open(const char* destination)
 {
 	final_name = destination;