diff --git a/imxml2epub.py b/imxml2epub.py
index 830d8ed..645e035 100755
--- a/imxml2epub.py
+++ b/imxml2epub.py
@@ -1263,7 +1263,9 @@ class FootnoteError(Exception):
         strImageFilepath = libeoaconvert.sanitizeImage(os.getcwd() + "/CONVERT/epub/OEBPS/images/" + strImageFileDir + strImageFileName, GM_PATH, TL_PATH)
 
         # Add copied file to contentopf
-        contentopf = addToContentopf(contentopf, "images/" + strImageFileDir + strImageFileName, strImageFileDir + strImageFileName, "jpg")
+        img_base_file_name, img_file_extension = os.path.splitext(strImageFileName)
+
+        contentopf = addToContentopf(contentopf, "images/" + strImageFileDir + strImageFileName, strImageFileDir + strImageFileName, img_file_extension[1:])
 
         # strSVGTemplate = """<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100%" height="100%" viewBox="0 0 573 800" preserveAspectRatio="xMidYMid meet"></svg>"""
         # xmlSVGFacsimile = etree.fromstring(strSVGTemplate)