diff --git a/src/opustags.h b/src/opustags.h
index 93c323b..720be29 100644
--- a/src/opustags.h
+++ b/src/opustags.h
@@ -124,8 +124,14 @@ using byte_string_view = std::basic_string_view<uint8_t>;
  *
  * 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 fclose_deleter {
+	void operator()(FILE *f) const noexcept {
+		fclose(f);
+	}
+};
+
+struct file : std::unique_ptr<FILE, struct fclose_deleter> {
+	file(FILE* f = nullptr) : std::unique_ptr<FILE, struct fclose_deleter>(f) {}
 };
 
 /**