diff --git a/user-doc/tutorials/cambridge.txt b/user-doc/tutorials/cambridge.txt
index bb3ff28e72527d1e744b942615a5494345997bdd..fa2df772ed3f7d291ac65ca69b4fb654b7cc8c3b 100644
--- a/user-doc/tutorials/cambridge.txt
+++ b/user-doc/tutorials/cambridge.txt
@@ -184,7 +184,7 @@ without further rescaling needed.
 
 We can plot the time evolution of the CVs along with the height of the Gaussian.
 
-\image html belfast-6-wtb6.pdf "Time evolution of the CVs and Gaussian height during the first 2.5 ns of a well-tempered metadynamics simulation with biasfactor equal to 6."
+\image html belfast-6-wtb6.png "Time evolution of the CVs and Gaussian height during the first 2.5 ns of a well-tempered metadynamics simulation with biasfactor equal to 6."
 
 The system is initialized in one of the local minimum where it starts accumulating bias.
 As the simulation progresses and the bias added grows, the Gaussian height is progressively reduced.