Only parse integer font sizes

2 files changed, 19 insertions, 1 deletions

diff --git a/mammoth/docx/body_xml.py b/mammoth/docx/body_xml.py
index 7bb8628..e65c5b2 100644
--- a/mammoth/docx/body_xml.py
+++ b/mammoth/docx/body_xml.py
@@ -81,7 +81,7 @@ def _create_reader(numbering, content_types, relationships, styles, docx_file, f
         font = properties.find_child_or_null("w:rFonts").attributes.get("w:ascii")
 
         font_size_string = properties.find_child_or_null("w:sz").attributes.get("w:val")
-        if font_size_string:
+        if _is_int(font_size_string):
             # w:sz gives the font size in half points, so halve the value to get the size in points
             font_size = int(font_size_string) / 2
         else:
@@ -602,3 +602,15 @@ def _add_attrs(obj, **kwargs):
         setattr(obj, key, value)
 
     return obj
+
+
+def _is_int(value):
+    if value is None:
+        return False
+
+    try:
+        int(value)
+    except ValueError:
+        return False
+
+    return True
diff --git a/tests/docx/body_xml_tests.py b/tests/docx/body_xml_tests.py
index 2258330..17d631d 100644
--- a/tests/docx/body_xml_tests.py
+++ b/tests/docx/body_xml_tests.py
@@ -336,6 +336,12 @@ class RunTests(object):
         run = self._read_run_with_properties([font_size_xml])
         assert_equal(14, run.font_size)
 
+    @istest
+    def run_with_invalid_w_sz_has_none_font_size(self):
+        font_size_xml = xml_element("w:sz", {"w:val": "28a"})
+        run = self._read_run_with_properties([font_size_xml])
+        assert_equal(None, run.font_size)
+
     def _read_run_with_properties(self, properties, styles=None):
         properties_xml = xml_element("w:rPr", {}, properties)
         run_xml = xml_element("w:r", {}, [properties_xml])