diff --git a/nefile/resources/icon.py b/nefile/resources/icon.py
index 0b89377..23247df 100644
--- a/nefile/resources/icon.py
+++ b/nefile/resources/icon.py
@@ -29,8 +29,7 @@ def __init__(self, stream, resource_declaration, resource_table):
     ##  An ICO extension will be added if it isn't already present.
     def export(self, export_filepath):
         ICO_FILENAME_EXTENSION = '.ico'
-        filename_extension_present = (export_filepath[:-4].lower() == ICO_FILENAME_EXTENSION)
-        if not filename_extension_present:
+        if not export_filepath.lower().endswith(ICO_FILENAME_EXTENSION):
             export_filepath += ICO_FILENAME_EXTENSION
 
         # CALCULATE THE IMAGE OFFSETS.