diff --git a/bob/bio/base/script/evaluate.py b/bob/bio/base/script/evaluate.py
index df1e74887fe81811dd5c637791013afe1cb642d1..9b1afb7a768c37470a163fee569019267e4f797d 100644
--- a/bob/bio/base/script/evaluate.py
+++ b/bob/bio/base/script/evaluate.py
@@ -29,7 +29,7 @@ import numpy, math
 import os
 
 # matplotlib stuff
-import matplotlib
+import matplotlib; matplotlib.use('pdf') #avoids TkInter threaded start
 from matplotlib import pyplot
 from matplotlib.backends.backend_pdf import PdfPages