diff --git a/sf-buffer/test/test_buffer_utils.cpp b/sf-buffer/test/test_buffer_utils.cpp
index e973601..435a56f 100644
--- a/sf-buffer/test/test_buffer_utils.cpp
+++ b/sf-buffer/test/test_buffer_utils.cpp
@@ -37,4 +37,11 @@ TEST(BufferUtils, get_filename)
             12344999);
 
     ASSERT_NE(result4, expected_file);
+}
+
+TEST(BufferUtils, get_file_frame_index)
+{
+    ASSERT_EQ(get_file_frame_index(12345000), 0);
+    ASSERT_EQ(get_file_frame_index(12345543), 543);
+    ASSERT_EQ(get_file_frame_index(12345999), 999);
 }
\ No newline at end of file