diff --git a/images.py b/images.py
index 35775f7..c1f0796 100644
--- a/images.py
+++ b/images.py
@@ -82,7 +82,12 @@ def get_apng_duration(file):
     dur = 0
 
     for frame, frame_info in img.frames:
-        if frame_info: dur += frame_info.delay*10 # convert delay from centiseconds to milliseconds
+        if frame_info:
+            # convert delay from centiseconds to milliseconds
+            if frame_info.delay_den == 100:
+                dur += frame_info.delay * 10
+            else:
+                dur += frame_info.delay * (1000.0 / frame_info.delay_den)
 
     return dur