diff --git a/src/libprs500/ebooks/lrf/html/convert_from.py b/src/libprs500/ebooks/lrf/html/convert_from.py
index 38f8947abe..0569d916a1 100644
--- a/src/libprs500/ebooks/lrf/html/convert_from.py
+++ b/src/libprs500/ebooks/lrf/html/convert_from.py
@@ -1248,10 +1248,11 @@ class HTMLConverter(object):
         except ValueError:
             pass
         m = re.search(r"\s*(-*[0-9]*\.?[0-9]*)\s*(%|em|px|mm|cm|in|dpt|pt|pc)", val)
-        normal = self.unit_convert(base_length)
+        
         if m is not None and m.group(1):
             unit = float(m.group(1))
-            if m.group(2) == '%':                
+            if m.group(2) == '%':
+                normal = self.unit_convert(base_length)                
                 result = (unit/100.0) * normal
             elif m.group(2) == 'px':
                 result = unit
@@ -1262,6 +1263,7 @@ class HTMLConverter(object):
             elif m.group(2) == 'dpt':
                 result = unit * dpi/720.
             elif m.group(2) == 'em':
+                normal = self.unit_convert(base_length)
                 result = unit * normal
             elif m.group(2) == 'pc':
                 result = unit * (dpi/72.) * 12