diff --git a/exercises/exerciseA/plot.py b/exercises/exerciseA/plot.py
index 4130224..715c1f8 100644
--- a/exercises/exerciseA/plot.py
+++ b/exercises/exerciseA/plot.py
@@ -7,8 +7,9 @@ threads, timings = [], []
 for file in os.listdir('timings'):
     with open(f'timings/{file}', 'r') as f:
         n, t = f.read().strip().split(',')
-        threads.append(int(n))
-        timings.append(float(t))
+        if n != 'None':
+            threads.append(int(n))
+            timings.append(float(t))
 threads = np.array(threads)
 timings = np.array(timings)