diff --git a/tools/src/CMakeLists.txt b/tools/src/CMakeLists.txt
index eacaa7ff..2b3043d4 100644
--- a/tools/src/CMakeLists.txt
+++ b/tools/src/CMakeLists.txt
@@ -1,3 +1,6 @@
+# libraries
+add_subdirectory(util)
+# binaries
 add_subdirectory(agb2mid)
 add_subdirectory(aif2pcm)
 add_subdirectory(asset_processor)
diff --git a/tools/src/util/CMakeLists.txt b/tools/src/util/CMakeLists.txt
new file mode 100644
index 00000000..eb28af93
--- /dev/null
+++ b/tools/src/util/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_library(util INTERFACE)
+target_include_directories(util INTERFACE .)
+
+# dummy target to make sure headers compile
+add_executable(util_dummy dummy.cpp)
diff --git a/tools/src/util/dummy.cpp b/tools/src/util/dummy.cpp
new file mode 100644
index 00000000..e64e616c
--- /dev/null
+++ b/tools/src/util/dummy.cpp
@@ -0,0 +1,4 @@
+#include "util/file.h"
+
+int main() {
+}
diff --git a/tools/src/util/util/file.h b/tools/src/util/util/file.h
new file mode 100644
index 00000000..e7054826
--- /dev/null
+++ b/tools/src/util/util/file.h
@@ -0,0 +1,18 @@
+#ifndef TOOLS_FILE_H
+#define TOOLS_FILE_H
+
+#include <cstdio>
+#include <memory>
+#include <string_view>
+namespace util {
+namespace {
+auto file_ptr_deleter = [](std::FILE* file) { std::fclose(file); };
+}
+
+using file_ptr_t = std::unique_ptr<std::FILE, decltype(file_ptr_deleter)>;
+
+file_ptr_t open_file(std::string_view filename, std::string_view mode) {
+    return { std::fopen(filename.data(), mode.data()), file_ptr_deleter };
+}
+} // namespace util
+#endif // TOOLS_FILE_H